German customers: For German Customers, your o2 credit does not expire once your o2 mobile phone number is valid. You can check the current validity period by dialing *102#. Make sure to top up once every 6 months so your number remains valid. Therefore, you can use up your credit within six months of topping up. With each new top-up, the validity of the entire credit is extended by another six months. If your phone number expires or you wish to deactivate it, you can easily withdraw your remaining credit. UK customers: Make sure to redeem your o2 Pay As You Go Top-Up within 12 months after your purchase. It will no longer be valid after 1 year. Additionally, once you have topped up your mobile device, you have 6 months to carry out a chargeable activity, or your mobile phone will be disconnected. After this time, you will lose any remaining balance on your account.