Google Play's return policy has always been a nice perk of being an Android user. If you don't like an app you've just paid for and downloaded, you can simply head back into Google's store, say you want a refund, and you're done. The amount of time you've had to make a decision on keeping versus returning has fluctuated in recent years, though; in the old days, Google gave people an entire 24 hours to initiate a refund. Clearly developers thought that was a bit extreme, and Google later drastically cut the timeframe down to just 15 minutes. That's where it's stood until now, but thankfully Google's return window is getting extended once again: Android users can now request a refund within two hours after they've downloaded an app or game.
So long as you're within the specified window, your payment method will automatically be credited with the 99 cents, $1.99, or however much you spent to begin with. If you still somehow miss it, Google recommends you take things up with the developer directly. You could make a reasonable argument that 15 minutes should've been more than enough time to make a call, but two hours is incredibly generous any way you slice it. Windows Phone lets willing developers give users a trial period for apps before purchase, but iOS lacks either option.