On Software Trials and the Mac App Store 

Rentzsch:

Software trials are loved by customers and developers alike. It’s easy to see why: customers get to try out first hand how an app works risk-free. Developers make their customers happier and reduce refunds. Yet, inexplicably, Apple doesn’t offer trials of any sort. In fact, their developer agreement forbids it. This is questionable policy for a $2.99 game, but inexcusable for a $60 Mac app.