ModelRefs / Memory (Agent) — AI Glossary
Memory (Agent) — AI Glossary
Persistent state that lets an agent recall prior interactions, user preferences, or task progress across sessions. Frameworks: Mem0, Letta (MemGPT), Zep.
Overview
Memory is typically implemented as a vector store of past turns (episodic) plus a structured store for extracted facts (semantic). Frameworks: Mem0, Letta (MemGPT), Zep. The hard problem is deciding what to forget without losing important context.
Reference details
| Topic | agents |
|---|---|
| Last reviewed | 2026-06-24 |
Related terms
Example: Memory is a retrieval problem wearing a different name
A support agent runs 40 sessions with one customer at roughly 12 turns each — about 480 stored entries. The next call retrieves the top 5 by similarity, so 475 are invisible, and similarity is not the ordering you want: the customer changed address in session 38, but session 3's address is textually just as similar and may rank above it. Working memory needs recency and precedence, not nearest-neighbour. This is why production memory splits into an episodic store of what happened and a small structured store of extracted current facts, where the address is a field that gets overwritten rather than a turn that gets re-ranked.
Commonly confused with
Three different things get called memory. The context window is what fits in one request and vanishes after it. Memory is state that persists between requests. RAG retrieves from a document corpus rather than from interaction history. A system can have a huge context window and no memory at all — that is the default, since the chat completions endpoint is stateless.
When to use it
Reach for it when:
- Assistants that must carry preferences or task progress across sessions
- Long-running agents, where the transcript would otherwise exceed any context window
- Where the same user returns and re-explaining is the main source of friction
Reach for something else when:
- Single-shot or stateless tasks — memory adds retrieval failure modes for no gain
- Without a forgetting and correction policy: stale facts are recalled as confidently as current ones
- For anything that belongs in a database — an order status is a lookup, not a memory
Continue your research
Use these connected ModelRefs sections to compare alternatives, inspect implementation paths, and review the evidence and governance boundaries relevant to Memory (Agent) — AI Glossary.
Frequently asked questions
What is Memory (Agent)?
Persistent state that lets an agent recall prior interactions, user preferences, or task progress across sessions.
What concepts are related to Memory (Agent)?
Closely related concepts include agentic memory, episodic memory, semantic memory, rag.