Recover Power Pack Purchase iOS (iPhone, iPad, iPod)
You can easily restore your Power Pack purchase by going to menu - settings - restore purchases.
The app then checks if you purchased with the Apple ID setup on your phone. If it finds that you did, the features will be unlocked instantly.
If the app still asks you to purchase after this, try one of these steps:
1) Double-check your phone is setup with the same Apple ID you purchased with. This is setup in your phone settings - iTunes & App store - Apple ID. Check that it matches the one on your invoice here: https://support.apple.com/en-us/HT204088
2) Try to signout of your iTunes account and then signing again. This is in your phone settings - itunes and app store - at the top.
3) Try to uninstall the app and then reinstall it again from your device using this link: https://itunes.apple.com/us/app/stronglifts-5x5-simplest-most/id488580022?mt=8
4) Try to purchase it again. If you already purchased with that account, Apple will recognize this and unlock the purchase instantly.
5) If none of this works, try to contact Apple directly about this. Here's the link: https://www.apple.com/support/itunes/contact/
Note that purchases are platform specific. If you purchase on iOS, it will work on any other iOS device (iPhone, iPad, iPod). But an iOS purchase won't work on an Android device (Samsung, Nexus, Motorola, LG, etc). Nor will a purchase from an Android device work on iOS. In this case you have to purchase separately for the other platform or you can use the app for free.