If the subscriptions were made in the German store, you shouldn't lose them.
You need a valid credit card issued by a bank in the country the store is in and you need a billing address in that country. If you have an account balance, either buy something more expensive and pay the balance with a credit card or contact iTunes Support and ask them to zero balance your account.
Region - Change your iTunes Store, iBooks Store, or App Store country or region.
If necessary, contact iTunes Support. Follow through the screens to get a chat or telephone option.
iTunes Support – world wide
Apple Support schedule phone call