> "if it ain't broke, don't fix it" is perfectly fine for the end user

That's okay, but in say, 2 years when Mac OS 28 completely bricks the app, the developer will not be there to give you an updated one (even if you're willing to pay), since most of the addressible market already bought the app in 2025, and after 2 years with almost no revenue, the developer stopped working on it, deleted the repo and moved onto another project. The developer can't even rely on a future OS update "encouraging" people to buy "App (N+1)" since it might be "ain't broke" for 1 year, or for 5.

The point of a subscription is not to rip you off, it's to acknowledge a few realities:

1. For reasons beyond developers' control, platform vendors do not provide a "permanent" platform, but a shifting one without any long-term guarantees. You can put a 100-year certificate into your app, but the OS vendor might decide that only certs with expiration less than 45 days are okay and your app no longer works unless you're around to (A) keep abreast of the platform's rules and changes, and (B) ship an update.

2. Many software offerings need to provide a server-side component, which is never a one-time cost.

3. Relying on upgrade purchases to sustain a product gives developers perverse incentives to shove a ton of new features just to be able to pitch "Upgrade to Appitron 2!" with a ton of bullet points, whereas subscription pricing incentivizes them simply to keep users loving the app forever, including adopting new technologies but also just improving the core experience.

Due to 1 and 2, it makes sense to let users who stop using the program after a short time pay very little, and to let users who rely on the continued operation of the program, pay a little bit each year, instead of paying $500 once and using it for a few years, and maybe upgrading for $250.