How to assign single id to mobile cordova app to use for settings

hi there, im building my first rather serious cordova android project.This app will be used throughout the country i am living in and as such i need a way to differenciate between each clientapp in order to load the appropriate default settings from the Meteor/mongodb server.Basically,on the first lime the app is launched,the client generates an id that it stores inside mongo and also in the app in a local file.on the second run,the app checks to see if this id exists in mongo if not it inserts it else it return the corresponging document allowing the user to change the settings of the app.

Help guys