App Session is defined as the total time elapsed between the app was opened and the app was closed by app user in a single session. App42 facilitates tracking of app sessions and can be enabled in just a single API call. Using this feature app developers can track total number of open sessions and average session time for the app.
This can be enabled using the following snippet
Once session tracking is enabled, you can see the current open sessions as well as average session time for your app. You just need to click App Insights > Current Active Session under Marketing Automation Console as shown below:
You can also track Average Session time as shown below: