In Letta that's referring to an LLM agent that has persistent memory (eg keep running the agent far beyond its context window limit, but maintain some persistent state to avoid derailment / enable indefinite use / learning over long horizons).

If you implement this persistent memory via tool use, then it's related to inserting/querying databases, because some agent has to read/write to a data store (potentially backed by a database) to maintain memories.

-charles from letta