Latest Google Maps have changed their policy. According to the new terms, an API Key is a must while you use it in a particular domain or an application created after 22nd June 2016.
Here are the steps you can follow in order to make your own google maps API key:
Follow this link in order to generate your key
Choose services like below image
Create new project or use existing project like image below
Create billing account.
Click to next for enable API’s
Click to My Projects and type your project name and select project by clicking on name of your project like image below.
Choose Credentials from left menu and create API Key like image below
Copy this key and paste in your Options Panel > Map Settings section like image below.
Add your domain name to the settings page like image below.
Please read below articles;
Choose Library from left menu and make sure you added below API’s
If you see a warning icon on your Apı Key, please choose Credentials menu from left menu then click on your Apı Key name