Currently I am integrating GCM 3.0 new registration process for push notification using InstanceID API.
Before that i am using GCM 2.0 register() method for push notifications and for that I have created project on Google developer console and created Server API key for sending push notification to Device
So now as i am migrating to GCM 3.0 by referring this link. while generating configuration file it asks two things:
By providing these two details it will Auto generate new Server API key but i have already created API key before that.
so is there is any need to change from old API key to new API key or stick to old API key?
No, you can use the old API key.
As the new process is just a New skin for building the API key and sender-id.