Retrieving previously purchased applications
Your application purchases are tied to your Google Account and can be installed an unlimited amount of times on any device. So, for example, if you remove "My Favorite Game" to save memory, you can reinstall it at a later date with no charge by simply visiting My Apps. You can also re-install apps from play.google.com from the My Android Apps section.
If you are being asked to purchase an application you have already purchased on Google Play on an existing or previous device, you might be using a different account than the one you were using at the time you made your purchase. Because the application is associated with a different Google Account, you are being charged to purchase it again. Additionally, if you are missing certain apps (free or paid), they might be registered under a different Google account. Fortunately, you can recover access to these apps by simply switching the account you