I am using Google Cloud Messaging for my Android application and I am trying to understand when the registration id expires. From this post I was able to understand that Goo
I am not exactly sure when GCM regId gets refreshed but, GCM Client documentation states that "Check if app was updated; if so, it must clear the registration ID, since the existing regID is not guaranteed to work with the new app version." So yes it might still be using old regId but, it's not guranteed that it will not have a new regId.