Yes but what we're looking at here is: can we use cognitive bias to increase the number of people who pay for the full version.

So you give someone a demo for free. They know it's a demo and they know it's free. They will be cautious about buying a full version.

But if you give them a game for free, and then they find out whilst using it that it's only a demo, they will experience "loss aversion" and are more likely to upgrade since people experiencing loss aversion are more likely to gamble as they try to reconcile their loss.

> Hopefully they get again in fashion

Android has <15-min "refund" (actually I wonder if this is a "undo" where the payment didn't actually took place and goes through after the timeout, like gmail's "undo send mail", thus avoiding a chargeback)

Also, IAPs allows one to implement the demo/trial/shareware model. Most implementations are poor though, making you think you have the full game/app but subtly (or not so subtly) crippling it beyond usability, or compromising the experience with ads.

The 15 minute refund isn't really long enough to decide if you like an app, and definitely not long enough for a game.

> (Hopefully they get again in fashion)

Windows Phone and Windows 8 allow developers to provide a trial mode for their apps, to give users a chance to decide if they like it.