The app is a “companion app” that can help the user operate their device, and provides an easy way to customize device settings and access video tutorials.
It also has a “Find” button that makes the device beep to help find it if it is lost.
The MyEye app also has a “remote control” interface for users who prefer controlling their device's functions through buttons on their smartphone.
The app is provided free of charge to help you use your device and control it's settings, from the convenience of your smartphone.
However, it isn’t essential for the device to be used with the app. Your device is easy to use, even without the app.