To restore your subscription, you need to log yourself in on all your devices by using the same account, e.g. via facebook, ON AIR or google+. If you did so, please open your settings and click "ON AIR without ads" and "Activate this device".
If this does not work, please click "Report new problem" and tell us when you purchased your subscription and which device you used to do so. We try to solve this issue as quickly as possible.