Error in installing google maps api key

I’m using transport theme http://edinataxi.net/edina/
I’m seeing this error This web site needs a different Google Maps API key. A new key can be generated at http://code.google.com/apis/maps/documentation/javascript/v2/introduction.html#Obtaining_Key.

But when I’m trying to sign up it shows “The API keys generated by this page are no longer available. Please see the relevant section below for the API you using”.
I’m new to this coding matter please help me.