With Google Play the purchases should become available if you follow these steps:
1. Make sure that you are logged in with the account that appears on your Google Play receipt.
- Open Google Play and tap the three bars in the top corner.
- Check the account that appears at the top of the menu.
- If it is not the correct account you'll need to add it through the device settings.
- Tap the drop-down arrow and choose the correct account from the list.
2. Delete and reinstall the app onto your device.
3. Launch the app, open the in-app Settings and tap the Restore Purchases button.