Is there a period of cancellation?

Yes. This is what our Terms & Conditions says:

Premium profiles or login accounts that have been assigned at least one premium profile may only be terminated by the parties with a notice period of two weeks prior to the end of the contractual term in question. Should the User not terminate a premium profile within the contractual term, the Contract shall be renewed automatically for the contractual term agreed upon.

You can manage your Premium subscription in your profile settings.