AppsFlyer's pre-install feature enables advertisers to track metrics for apps which are installed on an Android device at the time of purchase.
From version 4.5.0 and above of the AppsFlyer Android SDK, you can configure the /data/local/tmp/pre_install.appsflyer path in the manifest to allow the AppsFlyer SDK to track pre-installs.
<meta-data android:name="AF_PRE_INSTALL_PATH" android:value="/data/local/tmp/pre_install.appsflyer" />
The file to which the path points to should contain a key and a value - the key is the package name and the value is the origin of the app (e.g. Amazon). An example of the format of the file is as follows:
More details can be found here under Track App Installs Out of Google Play (Optional).
For details of how to Track Pre-Installed Apps using Android Property System, click here.