What very old/unmaintained software do you still use today, and why?
I still use Font Renamer to manage my font collection. It works great but hasn't received an update since 2008. Even the website looks straight out of the Windows XP era.
I got lucky and was able to buy YNAB on Steam nearly 10 years ago for as much as they're charging now for a single month of their subscription. Manually exporting/importing transactions can be a little tedious sometimes but in comparison there's no way I could justify that high of a subscription cost