After registration you automatically have the Free Account with no fee at all. You can choose to upgrade to Premium Account at any time in your bookmax.net settings.
The Premium Account with all features of bookmax.net is available for different time periods. The periods can be extended at any time. When your payed time period ends, your account is set back to Free Account.
To update your Free Account to Premium Account, please login to bookmax.net, go to "Settings", select "Account" and click an the desired time period. After Paypal Payment you are redirected to your updated Premium Account.