Google is soon adding a small amount of metadata to every APK coming from the Play Store. This will allow Google to verify that the APK is legit, even if the APK was not downloaded directly from the Play Store.
This feature is more for areas where mobile data is limited and peer-to-peer sharing of APKs is common. If these APKs have the metadata, they can be confirmed safe even when the device is offline and later updated via the Play Store.
This not only helps people get safe and updated apps, but it also helps developers as the app registers as added to one’s Play Store library and makes sure your apps aren’t stuck on an older version. Plus developers don’t need to do anything for this new feature to work.
Hit the source link for more info!