You do not need an API key to use the Goolge Maps V3 APIs. However, we just ran into a problem when Google reported that we exceeded our limit, although we did not (Development Server). I went ahead and set up the API key, and this is really useful because you then get a usage report. In addition, since then we have not seen the problem of using a false quota. I thought I would continue the process:
Go to https://console.developers.google.com/
Click the red Create Project button
Give your project a name and Google will automatically provide it with an identifier
Wait until Spinny at the bottom informs you that your project is completed.
In the left navigation bar, select API API and Auth and select "Google Maps JavaScript API v3"

Click the link and then enable the API


Go to the credentials in the API and Auth section and click the red "Create a new key" in the "Open API" section. Then click the Browser Key button.

Make sure you include an asterisk in the name of your site. For example, use mywebsite.com/*. This ensures that all pages are allowed to use the API.
Copy the key into the Javascript link on the Google Maps API, for example:
<script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?key=YOUR_KEY"></script>

In short, a key is not required, but best practices mean that you must use a key.
Mr. B
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