Sure, but if it's just a free version with a single in-app purchase that unlocks key features, then it's not a demo, a trial, or a test app, so they won't run a

Sure, but if it's just a free version with a single in-app purchase that unlocks key features, then it's not a demo, a trial, or a test app, so they won't run afoul of that. As proof, there are many "Lite" and "Full" versions, and I have seen a few apps that you unlock with an in-app purchase. So obviously this isn't a concern at the moment.