Don't worry! You can simply restore them without having to pay again as long as your device is connected to the same iTunes/Google Play account.
*Note: This only works if you do not switch mobile platforms (e.g. from iPhone to Android phone or vice versa). If your new device is on another platform, please contact us for further information.
To restore previous purchased items, please:
1. Go to the Settings page
2. Tap the "Restore purchased items" button on the list (see screenshots attached)
For iOS users, you can also try:
1. Go to Store
2. Tap "My Items" tab on the top
3. Tap "Restore purchased items" at the bottom