Last Thanksgiving (I know, this is going back a bit lol), we held an impromptu pinball tournament at home where we needed to keep track of three players and who won the best of 7 games between the three of us.

A quick Google play store search led to a mobile app called Multi Counter.
There is an ad-supported version of this app, which is the version I chose and the ads were small and not intrusive on the bottom of the screen. For $2.99 you can optionally purchase the pro version and remove these ads forever.
Inside the app you can create custom groups, which I called “three players” and created three counters and when one of us won, I just clicked the “+” to increment the counter.
A simple, but effective “who won” counter. Am sure there are other counters online and elsewhere, but it served the purpose well enough. What apps, online programs, or just plain old pen and paper have you used for game situations like this?