Google has changed the way their maps API keys work (and are now charging for it, if the usage gets too high).
These are the steps to generate your own Google API keys:
Create a Google account https://accounts.google.com/signup/v2/webcreateaccount?hl=en&flowName=GlifWebSignIn&flowEntry=SignUp (if you don’t already have one)
Click on Get Started https://cloud.google.com/maps-platform/pricing/sheet/ (you can get a free trial)
Select Maps and Places as services https://cloud.google.com/maps-platform/pricing/sheet/?apis=maps,places
Enter your credit card details, and follow the remaining steps