Where is the Postman documentation?
Open the maintained public collection documentation.
https://documenter.getpostman.com/view/55991899/2sBXwtrASmHow should the key be configured?
Create a private environment variable such as IPROUT_API_KEY and reference it from the Authorization header. Keep the current value out of exported collections.
Which requests should I test?
Test caller lookup, the 8.8.8.8 explicit example, usage, an invalid address, and a request with no key.