Payment is via PayPal.com. You can use your PayPal balance, your credit card or your bank account (in some countries). You do not need a PayPal account to make payment via credit card.
The link above creates a monthly subscription in Paypal to ensure you lock in your campaign.
If you wish to cancel a campaign at any time you must cancel your subscription manually at PayPal.com. There are no refunds once payment is submitted.