Memory-Map for All is an immersive full-screen app. That means that you may not see some of the system controls such as the "Home Bar" that you are used to seeing on your device.
On both iOS and Android, you can access the Home screen by swiping twice up from the bottom of the screen.
If you want to turn off the full-screen feature so you can see the system controls and use them with a single swipe, there is a switch in the Menu > Settings > Display Options.