Stateful Agents

Agent Memory

What is agent memory, and how does it work?

Agent memory is what enables AI agents to maintain persistent state, learn from interactions, and develop long-term relationships with users. Unlike traditional chatbots that treat each conversation as isolated, agents with sophisticated memory systems can build understanding over time.

The MemGPT Approach to Memory

Letta is built by the creators of MemGPT, a research paper that introduced the concept of an “LLM Operating System” for memory management. The base agent design in Letta is a MemGPT-style agent, which means it inherits the core principles of:

  • Self-editing memory: Agents can modify their own memory using tools
  • Memory hierarchy: Different types of memory for different purposes
  • Context window management: Intelligent loading and unloading of information

Types of Memory in Letta

Letta agents have access to multiple memory systems:

Core Memory (In-Context)

Fast, always-accessible memory that stays in the agent’s context window. This includes:

  • Persona: The agent’s personality and role
  • Human: Information about the user
  • Custom memory blocks: Additional structured information

External Memory (Out-of-Context)

Long-term storage for large amounts of information:

  • Conversation history beyond context limits (e.g. “recall memory”)
  • Vector databases for semantic search (e.g. “archival memory”)
  • Uploaded documents and files

Why Agent Memory Matters

Effective memory management enables:

  • Personalization: Agents remember user preferences and history
  • Learning: Agents improve performance through accumulated experience
  • Context preservation: Important information persists across conversations
  • Scalability: Handle unlimited conversation length and data volume

Memory Management in Practice

Letta provides multiple ways to work with agent memory:

  • Automatic management: Agents intelligently decide what to remember
  • Manual control: Developers can directly view and modify memory blocks
  • Shared memory: Multiple agents can access common memory blocks
  • External data sources: Connect agents to files, databases, and APIs

Memory blocks are the fundamental units of Letta’s memory system - they can be modified by the agent itself, other agents, or developers through the API.