Ideally, I think a T should keep notes that they can review before a session. I don't expect my T to remember a lot and will often, without his prompting, simply include refresher information as a matter of course. I know he remembers more than I probably give him credit for, but six years is a lot of information.

He remembers the main things, but sometimes bits and pieces get lost in translation. Some people have a mind for detail, like me (which was vital for me growing up), others don't. I suck at remembering things long term unless I have a regular relationship with someone. I will literally forget someone's name within a year if I haven't interacted with them in some form.

I would probably have to keep a very detailed log book if I were a T.