I logged with AIM which was a pain, at least for the late 90s version I was using, bc you had to save each chat manually. Then a Kramer-like friend wandered over when I wasn't home, got on my computer, came across the saved chats, and deleted them all. I did this kind of self-logging for the same sort of navel-gazing reasons as the OP but it really turned off friends, who thought it was about keeping a file on them.