I want to buy something and have it be left alone without trying to steal more money from me for the thing I already bought.
The only possible valid excuse for a subscription to software is services that cannot possibly exist without meaningful spending on server infrastructure. If that's cloud storage as the core of the purchase of the app, computations that are literally impossible to do locally or rely on data that's expensive to maintain, a subscription is legitimate.
If it's anything else it's shitty and you're a shitty person for doing it. Sell actual upgrades when they're actually upgrades, without stealing access to what people bought. It's the only acceptable model.