OK, so make sure you have the latest version (3.3.2 on iOS, 3.3.1 on Mac) installed. Also make sure you are connected to the internet and logged in to the AppStore with the user account you used to make the In App Purchase. Check in your App Store purchase history that the In App Purchase "Unlock Full Version" is visible.
Now, try again to Restore Purchases in Stage Traxx. If this does not work, please tell me what exactly happens. Do you get an error? Can you maybe post a screenshot here?
What you can also try is to repeat the purchase. Don't worry you will not be billed a second time if you already bought the Unlock Feature. That's why you need to check if it is visible in your purchase history.
Also make sure you are running the latest OS version. And you can also try to reboot your device.