How does the memory function work?

That is the version I use on iOS with a pro account 1.2024.163 (9522135661)

Sometimes I open a new voice chat and I ask: “What do you know about me?”
And it replies with some facts and topics hidden in any of the other 1000+ chats from recent year activity. Even when using model version 3.5

Other times it doesn’t remember anything.
In the settings there is no control that allows adding deleting or otherwise manipulating a memory setting.

Any explanation or experience?