Homey apps add tremendous capabilities and functionality to Homey. Because devices and services also change, and apps improve, it is impotant to be up-to-date with your Homey apps.
This is why Homey automatically updates your apps when a new version is in the Homey App Store. This makes sure you always use the most recent version of the app that is compatible with your Homey.
Note (for developers): Only apps installed through the Homey App Store auto-update. If you install an app in another way, for instance with the command line tool, it will not auto-update.