Regardless of which subscription length you choose, the subscription is always paid in advance. Automatic subscription renewal is activated by default if the purchase is done via a credit card or PayPal account.
If you pay for a six-month subscription (€6.99/month), you will be charged €41.94. Once the payment has been received, 6 months of subscription time (186 days) is added to your account.
The same rule applies when buying a 12-month subscription (€4.99/month). You will be charged €59.99. Once the payment has been received, 12 months of subscription time is added your account (366 days).