in-app-billing
Android IAB. Error – Authentication is required. You need to sign into your Google Account
I believe that Google now requires that the app is published as alpha version and a Google group specifically for testing is set up. I wasn’t able to find this information in the official documentation (which means that Google probably didn’t update it in quite some time), but here: https://help.gamesalad.com/hc/en-us/articles/203536123-7-6-In-App-Purchases-IAP-for-Google-Play