To test how your code uses the Bango Subscriptions API:
Use the test credentials Bango Support provided to you. (Contact Bango Support if you don't have the credentials.)
Send a test product catalog to Bango Support. This catalog can be the same as your catalog on production, or different: it's up to you.
Use the test credentials when making Bango Subscriptions API calls, so you create and manage subscriptions for products and plans defined in your test product catalog.
Bango Support provides you with production credentials when your testing is complete and verified.