Leanplum runs a job every 24 hours to check if each user’s push token is still valid. Based on the response we get back from Apple or Google, we can determine whether the user still has the app installed or if they have deleted the app from their phone.
We count an Uninstall only if the response indicates that the user's push token is Unregistered (which is caused by a user uninstalling the app).
If we get a failure response, we will discard the user's, now expired, push token -- in compliance with Apple's and Google's policy. In this case, or if the user has disabled notifications or the token is invalid for any other reason, Leanplum will not track this as an Uninstall.
See enabling uninstall tracking if you would like to activate this out of the box feature in your app.