Android Police reports that the feature has now been explained in Google Play’s Develop Console support documentation.
Developers can generate up to 500 codes per app each quarter, which are valid for up to a year. That includes codes for paid apps as well as in-app purchases. Unused codes don’t carry over to the next quarter, which means you can only create a total of 2,500 codes a year for your app.
You can set expiration dates for your codes, or pause them so they can’t be redeemed until you flip the switch back. It’s also worth noting that promo codes don’t apply to subscription-based content, like magazine issues.
Expect to see Android developers start to hand out codes to their apps in the near future.
We’ve contacted Google to learn more and will update this post when we hear back.