Not really an app, but a file which was always named the.log - only the location would change. That's an equivalent of scratchpad, but I rather early wrote a bit of a routine tied to ctrl+F9 in setkey.prg, which would open it, write down the file's last datetime as "-- closed at dddd-tttt", and then open a new entry with machine name, username, datetime, new paragraph.
Presently (2019) found 116 such files in my work directory, not counting those which exist only inside zips. There are duplicates, of course, and partial duplicates (when everything gets copied from one place to another and then the updates continue independently).
The format of the date wasn't consistent until 2001 (when I started the gig with Paige), so using those files as source of material for this writing will present some trouble, but hey, not the first time that I build obstacles for my own use.