Taken from the Crashalytics SDK FAQ:
If you have an Application subclass, then you can place Crashlytics.start() in the onCreate() method there! Otherwise, if you have multiple launch activities in your app, then add Crashlytics.start(this) to each launch activity. Crashlytics is only initialized the first time you call start, so calling it multiple times won't cause any issues!
http://support.crashlytics.com/knowledgebase/articles/206230-can-i-move-crashlytics-start-this-
With this in mind, I think that having started Crashalytics on your onCreate
method of you launch activity will suffice. Bugsense does more or less the same things and It´s started on the launch Activity only.