If you have more than one device, if you have bought a new device or if you have done a full reinstall on your current device it is possible to restore your in-app purchases on a fresh copy of the game.
If you had enabled Cross-Purchase on your old device, just do the same again on the new device using the same App Store and Steam accounts and your Wallet will contain the same items as before.
If you did not have Cross-Purchase enabled, just ensure you are signed into the same account on the new device when you start the game, then tap the “Restore Purchases” button in the Store.