Do you find you really need that level of “resolution” with memories?
On our [1] chatbots we use one long memories text field per chatbot <-> user relationship.
Each bot response cycle suggests a new memory to add as part of its prompt (along with the message etc)
Then we take that new memory and the existing memories text and feed it to a separate “memory archivist” LLM prompt cycle that’s tasked with adding this new memory and resummarizing the whole thing, yielding a replacement for the stored memories, with this new memory added.
Maybe overly simplistic but easy to manage and pretty inexpensive. The archiving part is async and fast. The LLM seems pretty good sussing out what’s important and what isn’t.