--- title: "How ChatGPT Memory Works" description: "How ChatGPT memory works as of September 2026: saved memories, reference chat history, the memory summary, what memory full means, and how to clear it." canonical: https://past.dev/blog/chatgpt-memory date: 2026-09-02 category: Research authors: The past.dev team --- # How ChatGPT Memory Works ChatGPT memory is the account-level layer that carries context between conversations. As of September 2026 it works like this: with memory on, ChatGPT automatically remembers useful context from your chats, uploaded files, and connected apps, and it maintains an editable [memory summary](https://help.openai.com/en/articles/8590148-memory-faq) of what it knows about you. This system began rolling out on June 4, 2026 and replaced the earlier pair of mechanisms, discrete saved memories plus a reference chat history setting, which survives as a legacy option ([release notes](https://help.openai.com/en/articles/6825453-chatgpt-release-notes)). Every claim below links to OpenAI's documentation. ## What ChatGPT memory stores and where to see it - Memory controls live in Settings > Personalization > Memory, where you can enable or disable memory at any time; when enabled, it draws on your chats, files, and connected apps ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). - The memory summary shows what ChatGPT remembers, updates automatically as you chat, and shows a last-updated time ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). It is a synthesis rather than a complete inventory: some details never appear in it, and the documented way to check a specific fact is to ask in chat ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). - To edit it, type the change into the text box at the bottom of the summary, or highlight any text to make a specific correction ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). - The book icon under a response lists the sources that personalized it (custom instructions, past chats, files, memories), each with an explanation of why it was used ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). - Memory is stored separately from chat history, so deleting a chat does not delete memories created from it ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). ## Saved memories and reference chat history The system most searchers ask about ran from 2024 to mid-2026 and remains available under Settings > Memory > Saved memories ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). OpenAI defined its two parts on April 10, 2025: "saved memories" you ask ChatGPT to keep, and "chat history", insights ChatGPT gathers from past chats to improve future ones ([announcement](https://openai.com/index/memory-and-new-controls-for-chatgpt/)). Each part has its own toggle, and OpenAI's projects documentation still names both: "Reference saved memories" and "Reference chat history" ([Projects in ChatGPT](https://help.openai.com/en/articles/10169521-using-projects-in-chatgpt)). The dated evolution: - September 5, 2024: memory reached Free, Plus, Team, and Enterprise accounts ([announcement](https://openai.com/index/memory-and-new-controls-for-chatgpt/)). - June 3, 2025: Free accounts got a lightweight version that references recent conversations for short-term continuity; in the EEA, Switzerland, Norway, Iceland, and Liechtenstein it is opt-in at Settings > Personalization > Memory > Reference chat history ([release notes](https://help.openai.com/en/articles/6825453-chatgpt-release-notes)). - October 15, 2025: ChatGPT began managing saved memories automatically, keeping relevant details prioritized and moving less important ones to the background ([release notes](https://help.openai.com/en/articles/6825453-chatgpt-release-notes)). - January 15, 2026: with reference chat history enabled, ChatGPT retrieves specific details from past chats more reliably, and any past chat it uses appears as a source ([release notes](https://help.openai.com/en/articles/6825453-chatgpt-release-notes)). - June 4, 2026: the current system began rolling out to reduce stale and contradictory saved memories, with increased memory capacity for Plus and Pro ([release notes](https://help.openai.com/en/articles/6825453-chatgpt-release-notes)). OpenAI's stated reason for the redesign is that manually managed memories went stale and contradicted each other, citing "I'm training for a marathon" coexisting with "I sprained my ankle" ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). Keeping [facts that change over time](/guides/facts-that-change-over-time) current is a general memory problem well beyond ChatGPT. Depth also varies by plan: the [pricing page](https://chatgpt.com/pricing) lists limited memory on Free, "Longer memory" on Go, "Expanded memory and context" on Plus, and "Maximum memory and context" on Pro. ## What ChatGPT memory full means and how to fix it The memory full notice belongs to the legacy saved memories system. That list has a fixed capacity: OpenAI's October 15, 2025 release note describes automatic memory management as a way to keep saved memories from "reaching capacity" and avoid the "memory full" state ([release notes](https://help.openai.com/en/articles/6825453-chatgpt-release-notes)). OpenAI does not publish the capacity itself, and users report that once the list is full, new memories stop being saved until space is freed ([OpenAI community thread](https://community.openai.com/t/chatgpt-plus-plan-memory-issue-no-warning-when-memory-is-full-leading-to-lost-entries/1111613)). Existing memories keep working either way, since saved memories are always considered in future responses until deleted ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). The documented fixes: - Delete individual saved memories you no longer need, or clear all of them, in settings ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). Deleting chats frees nothing here, because saved memories are stored separately from chat history ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). - Let automatic management work: since October 2025 it deprioritizes stale entries specifically to prevent the full state ([release notes](https://help.openai.com/en/articles/6825453-chatgpt-release-notes)). - Leave the legacy system: the June 2026 memory summary updates itself instead of filling a list, and Plus and Pro accounts received increased capacity ([release notes](https://help.openai.com/en/articles/6825453-chatgpt-release-notes)). Switch back and forth at Settings > Memory ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). ## Why ChatGPT forgets things inside one conversation Forgetting within a single chat is a different mechanism from cross-chat memory. Each model request runs inside a [context window](/glossary/context-window), a fixed token budget covering input, output, and reasoning tokens ([Understanding and counting tokens](https://help.openai.com/en/articles/4936856-what-are-tokens-and-how-to-count-them)). A conversation that outgrows the budget cannot pass all earlier turns to the next request: the window "limits the tokens a model can work with in a request" ([Understanding and counting tokens](https://help.openai.com/en/articles/4936856-what-are-tokens-and-how-to-count-them)). The [pricing page](https://chatgpt.com/pricing) documents the sizes as of September 2026: for default models ("GPT Instant") a total context window of 27K tokens on Free, 54K on Go and Plus, and 128K on Pro; for reasoning models ("GPT Reasoning") 256K on Go and Plus and 400K on Pro. Its footnote adds that ChatGPT manages a shared context window, and the space left for user input varies with the features in use and any memory content ([pricing page](https://chatgpt.com/pricing)). The two layers stay distinct: [cross-session memory](/glossary/cross-session-memory) persists between conversations, while the window is rebuilt on every request. ## Temporary chats, projects, and workspace controls - Temporary Chats start non-personalized: no memory, no custom instructions, and no new memories created; a personalized temporary chat can read existing memories but still creates none ([Temporary Chat FAQ](https://help.openai.com/en/articles/8914046-temporary-chat-faq)). Unsaved temporary chats stay out of history, though OpenAI may keep a copy up to 30 days for safety ([Temporary Chat FAQ](https://help.openai.com/en/articles/8914046-temporary-chat-faq)). - Projects offer default memory or project-only memory; with project-only, chats reference other chats in the same project and nothing crosses the boundary in either direction ([Projects in ChatGPT](https://help.openai.com/en/articles/10169521-using-projects-in-chatgpt)). Shared projects are always project-only ([Projects in ChatGPT](https://help.openai.com/en/articles/10169521-using-projects-in-chatgpt)). - On ChatGPT Business, memory is per account: workspace owners can disable it workspace-wide, and doing so deletes members' existing saved memories ([Memory FAQ, Business version](https://help.openai.com/en/articles/9295112-memory-faq-business-version)). Workspace data, including memories, is excluded from model training by default ([Memory FAQ, Business version](https://help.openai.com/en/articles/9295112-memory-faq-business-version)). - In ChatGPT for Healthcare and Enterprise regulated workspaces, improved memory is off by default and workspace admins choose who can enable it ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). - A log of deleted saved memories may persist up to 30 days for safety and debugging ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). ## What ChatGPT memory does not do Documented boundaries only: - It does not transfer between users: memories are tied to each account and cannot be shared with other members of a workspace ([Memory FAQ, Business version](https://help.openai.com/en/articles/9295112-memory-faq-business-version)). - Custom GPTs keep their own distinct memory, and builders never see yours ([announcement](https://openai.com/index/memory-and-new-controls-for-chatgpt/)). - Deleting a memory does not scrub past chats that mention it; those chats must be deleted separately ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). - Fully deleting a fact means removing every source it appears in: past chats, archived chats, files, the memory summary, and any connected apps that contain it ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). - The sources view may omit factors that shaped a response ([Memory FAQ](https://help.openai.com/en/articles/8590148-memory-faq)). The deletion and management flows are collected step by step in [how to delete ChatGPT memory](/blog/delete-chatgpt-memory), and the extension paths (Projects, custom GPTs, MCP in developer mode) in [how to add long-term memory to ChatGPT](/blog/add-long-term-memory-to-chatgpt). ## For builders: this memory belongs to ChatGPT past.dev is a memory API for assistants you build. It runs as a managed service or, on an Enterprise agreement, in your own cloud. `POST /api/v1/ingest` accepts timestamped source text, stable source metadata, an audience slug, and an author identity. Once ingestion completes, `POST /api/v1/recall` requires a query and identity and returns ranked documents with dates and source excerpts. Start with the [Memory API quickstart](/docs/memory-api/quickstart) and the [benchmarks](/benchmarks).