Your payment details can be updated by looking at the sidebar of your account page for the Update Payment Details button.
Please note that we only accept payment by credit or debit card at this time. We do not issue purchase orders. Generally, we also do not issue invoices, but please contact us if you have a Team or equivalent legacy plan if you have questions about this.

That will bring you to a page where you can update your payment details:

There you can update your card details to change where future renewal payments will be taken from. Note that you will not be charged when updating your details.
Viewing past paid invoices
If you cancel your paid subscription, you will no longer be able to view your past billing receipts. Please contact us if you need a copy for your records.
Updating VAT, billing address, etc.
If you need to add or update additional billing details to display on the invoices, please contact us.