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

Then click on Screen Shot 2016-10-11 at 16.36.27 on the upper right.

Then select “Create a new project”

Then you obtain your API key:

Click on the link “API Console”:

In the new window, for the Key restriction, select “None”.

Save and you’re all set!

Now you just have to copy and paste your API key in your app editor in Settings > Advanced.