Post-purchase subscriptions aren't necessarily bad, but the real death-knell is when they're combined with the profit motive. It hurts to realise that, no, your post-purchase subscription isn't paying for ongoing security updates; that it is the business model. It's why the subscription is $9.99 instead of $0.60, or whatever. The purchase price is just them double-dipping.
This. A subscription can work if a service is actually provided, as in regular updates, however I would say that's rarely the case and it's simply to make cash. Goodnotes, Pro Create, Affinity, all show you can make a fantastic product without a subscription and still bring regular updates.
