If you use the dashboard, you can see your current credit balance at the top of the page.
If you use the plugin, you can also see your credit balance at the top of the plugin.
If you also want to see what credits were used for, open Billing and check Credit usage in the dashboard.
Can’t see a balance or does the number look wrong? First check whether you are logged in with the correct account in the dashboard or the plugin. If that is correct, contact your administrator.