This how-to will walk you through signing up for a free Google Maps API Key.
1. On the Google Maps Geocoding API page, click “Get A Key” button
2. Select “create a new project” and click Continue.
3. Click “Credentials” tab.
4. Click “Create Credentials”, then select “API key”
5. Select “Server key”
6. Name the API key for example “My WP site”.
7. Copy the created API key
8. Paste it to Theme Setting > General > Google Maps API Key and save changes.