The Cloud App Licenser API now features an optional App Version System, which is designed to allow you to alert your end-users if a more recent version of your app exists, regardless of whether or not they are also notified by proprietary app store systems.
You can either use the dedicated App Version Check request to compare your end-users' locally-stored app version with those you have entered using your Dashboard, or you can optionally check for new versions using the License Get request. This is especially convenient if your app already carries out this request when it initiates.