Unfortunately we had to stop distributing vouchers for iOS (iPhone + iPad) due to store restrictions. If you still have an unredeemed voucher code (probably from an older promotion?), please contact us and send us your PlayerID (you can find it under Profile) and the code. We will redeem the code as soon as possible.
In the Android version, voucher codes can still be redeemed, but the input field meanwhile has moved from the "Shop" area to the "Profile" area. To redeem a voucher, please switch to the menu ("Burger" button, top left) and go to the Profile section. While there it is also a good opportunity to define a profile name... :)
PS: alternatively to the ticket you can also send us an email (firstname.lastname@example.org) or use our homepage form.