Here’s how to upgrade to the full version of Runtastic Butt Trainer Workout on Android for free ($6 value)

Popular fitness app developer Runtastic is running an interesting promotion right now on its Runtastic Butt Trainer Workout app for Android. The freemium requires you to buy in-app purchases in order to get the full experience, which will end up running you about $6. But today you can download the free version and then upgrade it to the full version at no cost using the following instructions: