Obtaining a Google Maps API Key

Google API key can be created here:

https://developers.google.com/maps/documentation/javascript/get-api-key#get-an-api-key

1. Click on the Google API Console button.

2. Log in with your Google Account

3. After you have logged in, it is necessary to confirm that you are accepting the terms of use.

4. If you are logging in to Google API Console for the first time, it is necessary to create a Project or to select the existing one. 

5. After creating a project the following screen will appear. Click on the API key. 

6. The key needs to be without restrictions. Enter a key’s name and click on the Create button.

7. The following APIs need to be enabled if they haven't been added already.

Google Places API Web Service
Google Maps JavaScript API
Google Maps Directions API
Google Maps Distance Matrix API
Google Maps Elevation API
Google Maps Geocoding API

You can do that by clicking on Library > Google Maps APIs and select the missing APIs.