I have followed google instructions for implementing in-app purchases service. 

I was provided access to Google Play developer console as invited user. 
I took private key from it, and added my google account to the input field with test accounts. After that I craetad APK file and signed it with valid certificate. Then uploaded application to Google Play but didn't publish it. After it I created needed in-app purchases and published them.
Then installed same signed apk file on my device.

Right after publishing in-app purchases and for some period of time my application was givin me message like "not found", but some time later it became available. 
And now I can buy all the items from the application, but no one else who installed the same APK file can't. 
I tried to add their email addresses into list of test accounts in profile - no luck, even the user owner of the Google Play account can't buy anything.
They keep receiving smth like "item you selected is not available for purchase"
When they try to buy test purchase item (the one that is described in documentation) they can successfult get "android.test.purchased: PURCHASED"

**My question is:** how can I test in-app purchases of unpublished app from different devices and accounts