If you like to flash ROMs or switch phones by upgrading I would pass along a bit of experience with the use of free Apps that ask for you to donate to get rid of ads. It is perfectly legal, but I don't like it and will never again donate to a "free" app. Here's why. Google will keep track of the pay status and will never again let you donate, which is good, but...if you change ROMs or phones and reinstall the app thru a backup, the licensing is not in the app nor the data...but Google Play doesn't show that it has been "purchased" because it IS a free app. So when you install it you are back to the ad version even though you paid for it. You are now at the mercy of email to the developer to reset YOUR license at his end. This is not acceptable to me. I've had problems get responses back from these guys. I am NOT saying don't PURCHASE apps, in fact I think these "free" apps should be pay apps from the start. Maybe put out a "Trial version." Out of app billing ensures you have a stored license that all you have to do is reinstall from google play or your back up. The app developers deserve to be paid for their work, but going about getting it through "in-app donations" is a real pain in the butt. As for me, I just won't do it from now on. If you are an app developer and you would like payment, ask for donations but don't link payment of donations to a better version (i.e. ad free) of your app. Put the better version up for sale like standard.