AndroidPublisher API return projectNotLinked error

Question

This happens when I was using Google Play Android Developer API in Google Developers Console to test the status of purchased product, and the result is always like this

Answer 1

After days trying to use API Explorer to use Android Publisher API but failed, I requested support from Google and receive the answer "It looks like API Explorer is no longer supported for the Publishing API". So basically I can't use API Explorer to check in-app purchase token again. Hope this help who's struggling with this.