Adding custom checkbox to customers field

I am trying to add a checkbox to each customer field in the admin environment. If this checkbox is checked, a payment method will appear when the customer is logged in.

Does someone know if there's an extension for this? Or should i code this by myself.

Thanks in advance.

Well in OpenCart you can set a customer group so that customers have to be approved before they can login and you can set your store so that only logged in customers can purchase, so that might achieve what you want?