Take a look at the pricing page. There you can compare the various membership models regarding functionality, promotion credits, pricing etc.
1. If you want to become a PRO member, go to your settings:
2. Go to Payment Settings and choose the yearly or monthly plan. When choosing the yearly plan you save 2 months:
Worldwide there are many payment methods to choose from, depending on your country
At the end of the booking period the subscription renews automatically for the same period at the same price unless you disable automatic renewal in your account settings.