Bókun collects subscription fees via credit card only. Here are more information on Bokun monthly subscription fee from Bokun's website
How to add credit card information to your Bókun account
To add your credit card to pay subscription fee to Bókun select the "Cog wheel in top right corner" then you select “Account & Billing” from the side bar:
Then add you credit card information in the Credit Card field. Note, that we at Bókun are never able to see your credit card information.
Your payment information is processed and stored by Borgun - our PCI certified payment provider. All communication between Bókun and Borgun are encrypted and secure.