The home/away for notifications are set up in the app. It's fully implemented in the Android app, but we're still working on the iOS app as there are a few bugs that they're working on solving alongside the beta testers.
You'd enable the notifications by tapping on the spanner on the right hand side of the senor and then select under Notify me either Always, Away or Off. If you select always, you always get notifications from a device/sensor, away means that you'd only get notifications when you set the Almond+ to away mode, either via the app or the Connected Sensors app in the LCD UI.
Hopefully this clears things up a bit.