I'd like to be able to buy software conventionally. That if I buy your app, 1.0, I can assume I'll get a year or two maybe of updates as necessary, but when you have a big release, like a 2.0, I am free to use the 1.0 version, but can upgrade to 2.0 at a new cost.

Then, my app doesn't go away because I stopped paying you. And I don't get free features forever. If I use your app and I want the new things, then I can pay you again for them.