I have an unpublished app on Google Play which I want to update for my existing users, but not let new users download it.
The Google Play documentation seems to be saying that this can be done by simply uploading an updated apk (and not re-publishing the app):
Unpublished Apps
Existing app users will still be able to receive app updates, even if you unpublish your app. If you don't want new users to find and download your app but still want to provide updates to your existing users, set your app to Unpublished in the Developer Console. https://support.google.com/googleplay/android-developer/answer/113476?hl=en
But it seems unintuitive that an "unpublished" application would work that way. If the documentation is correct, how does Google Play tell the difference between an 'existing' user and a 'new' user?
Just a follow up: pushing an update to the unpublished app does make the update available to existing users only, but the app does not update automatically for these users. They must browse to the app page, where the app will have an "Update" button which can be triggered manually.
(This is just speculation, I'm not affiliated with Google in any way or anything)
The existing user probably has the app associated with the Google account they use to log in to the Play store.
If you look at your own profile in the store, there's a list of all the apps you've ever installed. I'm guessing the update would be available only for people who have your app in their lists, and the app will still be invisible for new users.
Whenever a user that has the app installed wants to update it, he requests an update of the app, it's different from re-installing the app as data from the app (a save from a game, or some saved preferences etc) are kept untouched, google play can easily detect that since it can detect what apps you have installed.
来源：https://stackoverflow.com/questions/20474271/google-play-update-an-unpublished-app-for-existing-users-but-not-new-users