Currently, you will automatically receive a trial month when you first sign up for your Pro or Pro+ subscription. Within the first 30 days you can cancel your subscription free of charge if you don't like it. All functions of this subscription will be available until the end of the trial month. The trial month ends afterwards without any costs for you.
If you do not cancel within the trial month, the purchase price of the selected subscription will automatically be charged after 30 days and through the payment method you specify.
What you have to do when you are in the trial month and receive a voucher is described here.