In my experience, the “lifetime” fees are tied to the Apple ID, so it should move devices with you, so long as you have access to that Apple account. And if not, that’s at least how it works on Android.

Not to say the price is fair at $80…I think before the Reddit 3rd party stuff, I’d paid for a fair few Reddit apps for no ads, but it was to support a product I liked, and it was maybe $6 at most for it per app. I probably wouldn’t go above $15, and it would have to be a really good app…