> There is no mechanism to make paid updates possible. Sure there is! Quite a few apps are delivered as separate numbered versions, like Acorn 4, Acorn 5, Acor

> There is no mechanism to make paid updates possible. Sure there is! Quite a few apps are delivered as separate numbered versions, like Acorn 4, Acorn 5, Acorn 6, Textual 7 etc. That's how software used to work a millenia ago. Yearly updates that you would buy separately should you chose to. Most of the time I can still download older versions even if they're not listed on the App Store.