Starting with Android Studio 3.0 Canary 1, you have now some options of devices that come with the Play Store app built-in (like Nexus 5X and Nexus 5 on image below).
Also, you should use a system-image which targets “Google Play” (instead of Google APIs),
as said images come with “Google Play” pre-installed, and you can just like a real device open “Google play” and update it.
Update 2022; but even with above, you cannot use the Emulator to test Google Play Billing:
- You must install your application on a real device to test Google Play Billing,
- Or, ask Google for “closed testing” permission.
see How to test In-app Billing on an emulator?