Making demos is usually a net loss for developers. There are few scenarios where the extra time and effort put into a demo actually result in increased sales [0].
I wasn't talking about "making demos". I was talking about native support in the platform to limit usage of an app to a certain time. The developer just clicks a checkbox "make 24 usage hour demo available" and that's it.
[0] https://www.youtube.com/watch?v=7QM6LoaqEnY