In a recent move to reduce unnecessary notifications, the Play Store no longer confirms when apps are updated in the background. While this may not be a big deal for most users, it's understandable some people want to be notified when their apps have been successfully updated. Thankfully, AppNotifier solves this problem, as it can send similar notifications to what the Play Store used to do when apps are updated.
As notifications are no longer sent by the Play Store, AppNotifier listens for app installs and updates. When an app is installed or updated, it triggers a notification, just like the Play Store used to. You can even select to be notified for sideloaded apps, which is handy if not all your software comes from the Play Store.
You can grab AppNotifier directly from the Play Store or download it from APK Mirror.