You can use the Google Maps service freely on commercial sites unless they are closed communities (ie on an entirely private intranet, or on a site which is
only accessible by paid subscription). If the public can access your website you should be ok, check the Google FAQ on this as it is much clearer than the full Terms:
https://developers.google.com/maps/faq#tos
You do not need a GoogleMaps API key for everything in the ujGoogleMaps module to work. However, you will want to obtain an API Key as using one raises the number of free map loads permitted per day and gives access to analytics in the Google Webmaster Control Panel. When you have an API key enter it into the field on the ujGoogleMaps Global Config tab in the Admin CP.
Current usage limit (with API key): 25000 map loads per day. If you exceed this for more than 90 consecutive days Google will limit your access to their API. Note that Google's count of map loads counts more than just loading a map. For more about this and current limits read this Google Maps FAQ: Usage Limits:
https://developers.google.com/maps/faq#usagelimits
Quote: Note: Applications deemed in the public interest (as determined by Google at its discretion) are not subject to these usage limits.
There is a config setting to force static maps throughout the site. Unless static="false" is set in the smarty function each map will be shown as static. There is a gotcha here, the max static map dimensions are 650x650, so it would be good practice to add static="false" to any large maps or maps where the interactivity is a core feature on your site. Then you would be able to switch on Forced Static maps without messing up the layout or core functionality of your site. Note that them maps in the control panel are not forced to static so that addresses can still be geocoded and the items created with the necessary data.
Set the Force Static Maps config setting to "Force Static Maps" under global config. Note that if you do not have a width set on a map it may show at a different width to the responsive version depending on your skin.
Further info in Googles static maps documentation:
https://developers.google.com/maps/documentation/staticmaps/