To update your credit card and other billing information:
1) After you log into your dlvr.it, go to Settings by clicking your avatar
2) Click Account Settings
3) Click Billing Info
4) Click Update Billing Details
5) Update the credit card information and submit the information
If updating PayPal, select Paypal and follow the onscreen prompts. Please also make sure that all pop-up blockers have been disabled if you're attempting to use PayPal.