I've held a grudge against the Android app "DaTuner" for literal years now, because at one point I paid what was then a one-time fee to remove ads from the app. I used it for years as a very handy and useful tuner. And then, they added a subscription.

YOU ALREADY GOT MY MONEY!

Since then, I have just used the built in tuner in the Ultimate Guitar app - which is inferior, but I'm not paying a subscription for a single-purpose app like a guitar tuner.

This happened like 8 years ago and I'm still annoyed by it.