There's more than one way to get free credits and discounts in the Google Play Store for apps, games, books, movies, in-app items, and other Play Store content. You may know a few of them — but some of these may surprise you. When it comes to spending on apps, games, and in-app purchases, Apple's app store has consistently outperformed Google's, earning nearly double the sales annually. While you'd be hard-pressed to find free credits and deals for the Apple App Store, the opposite is true ...| Gadget Hacks