The first step to restoring your purchase is to check which app you downloaded. There is a free trial version with a "Premium" in-app purchase upgrade and a "Premium" version that you purchase right when the app is downloaded. If you are not sure about which app you initially downloaded, you can always check this by doing the following:
On your device, tap Apple's "App Store" app then go to Updates > Purchased (listed at the top of the page) and find our app. If there is a "+" in the app name, this is the "Premium" version. If there is no "+" then you downloaded the "free" version and purchased the "Premium" upgrade as an in-app purchase.
Follow the prompts to install the app.
If you need to restore your in-app purchase for the free version you can open the app, tap the "BUY" button and then the "Restore Your Purchase".
Please contact us if you have any questions.