We recommend you to update your billing details at once.
Go to Billing, click Add payment method and save your card. 

You can pay for every order manually at once  or every time you have reached $20.00 you will get the bill. Your next bill will be sent on the 1st day of every month or if you reach $20.00 in outstanding charges.If you reach  $20.00 in outstanding charges in total, a bill will be issued immediately. View outstanding charges.

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