As I recall, it did keep such records, if for no other reason than there was some degree of personalization that went on. The people higher up the food chain tended to be the ones that taught it more clever words and phrases.

My memory's fuzzy on the finer details, but I do recall a "bad words" list of things it would ignore in human input hardcoded somewhere. But of course, that just meant people would find out the hard way they weren't safe to type whatever they wanted.