To create your Google Maps API keys:

Go to https://developers.google.com/maps/documentation/javascript

Then click on  on the upper right.

Create or select a project:

Create a billing account if you don’t have one (this is mandatory):

The account is automatically awarded with the free trial 300$ limit:

Once you have filled the billing form, hit the “Start my free trial” button.

Select the 3 options and click on Next:

Answer the questions and click on Next:

Enable your API key:

Copy your API key and click on API Console to set the restrictions:

In Key Restrictions > API restrictions, select “Restrict key” and select the following APIs:

Save and you’re all set!

Now you just have to copy and paste your API key in your editor in Settings > APIs: 

just enter the api key there and then save. Thats it!