Follow these instructions for Android apps as well as Unity Android apps.
Create a Google API project and enable GCM
In order to enable push, you need to create a Google API project and enable Google Cloud Messaging (GCM). You'll need to make a note of your project number and API key for integration.
Enable or disable Localytics Push
You can disable/enable Localytics Push programmatically by making a library call to Localytics.setPushDisabled(boolean disablePush).