Look at Claude code's "automemory" for example, they don't use a vector database or anything complex. Its just simple markdown files on the local filesystem along with grep for retrieval and it works great for me.
For many simpler use cases, simple techniques like context summarisation are good enough.
gregzem•1h ago
anshmalik2002•33m ago
Especially now that building a simple memory layer particular to your use case won't take a lot of time and effort. And you can keep making it better as you go forward.