Hello Marcus,
please see here for the description on how to activate this:
http://www.howtoforge.com/howtoforge_supporter_howto
It is also possible that the payment is not completed yet so that the subscription is not active yet. If you selected credit card for the payment, it takes a few minutes (maybe up to an hour) to complete, if you selected eCheck, it may take up to 5 days. You can see the current payment status of the transaction in your paypal account.