You can upgrade your account with a PayPal account or any major credit card, and it's really easy.
Once you figure out which upgrade is right for you (Which upgrade should I buy?), choose the plan, billing frequency (monthly, yearly, or biennially), and your form of payment: credit card or PayPal.
Choosing PayPal will open a new window for you to log in and connect your account.
Follow through the PayPal prompts until you return to the POWr upgrade panel and click Complete Payment to confirm your purchase.