In the older version of the API, I'd have to insert the javascript into the page using something like this for just basic functionality to work:

http://maps.google.com/maps?file=api&v=2&key=GoogleMapsAPIKey

Where I had to configure the API key for each individual site. Looking at the documentation, it says to get a basic map working I just need this:

http://maps.google.com/maps/api/js?sensor=true/false

Where does the API key fit in? Do I need to worry about it if I just plan on using a basic map and marker and none of the more advanced functions?