You may wish to allow customers to only make purchases from your site using credits. If so you can set the settings in the Fast WooCredit Pro payment gateway to create a credit only store.
Go to WooCommerce Settings and then to the Payments tab.
Click the Manage button next to the Fast WooCredit Payment gateway.
Scroll down and make sure the credits only store checkbox is marked as ticked. Click on Save Changes.
Now you have a fully functioning credits only store.
You can view a full tutorial on the Fast WooCredit Pro payment gateway here.
You may also choose to allow customers to instantly purchase the credit product and bypass the shopping cart altogether. Check out the Instant Credit Purchase tutorial here.