# Memory layers for AI agents — The Agents Index

> Source: https://theagentsindex.com/category/agent-memory (curated, re-verified)

Memory layers that let an agent remember users, facts and past sessions across conversations.

1 agent in this category, A to Z. Each name links to its answer-first markdown twin.

| Name | What it is | Pricing | API |
| --- | --- | --- | --- |
| [Letta](https://theagentsindex.com/letta.md) | Stateful agent harness, cloud and SDK for agents with persistent, git-versioned memory. | Free, then $20/month | Yes |