Within Teamwork CRM, you can update your payment details via your subscription settings.
Click your profile icon in the top right of your site and select Settings from the dropdown menu.
In the Settings area, select the Subscription tab in the left navigation pane.
In the Subscription settings, you will see an option to update your payment details below your subscription summary.
You will be brought to the checkout area where you can put in your updated payment information, as well as contact details and any changes in billing address. You can also add a tax or VAT number here (if applicable).
Click Update to complete the changes to your payment information.
For more information, see: Adding or Removing Users from Your Subscription