If you find that you’re reaching the limit, there are some workarounds:
You can purchase Google Maps for Business from Google. They will give you an API key with a much higher limit (100,000+)
However there doesn’t appear to be a way to for Mappress to send the API key with the request to Google. This would be simple to implement, by adding this as a property of the Mappress_Obj that is set from the value in the admin page. This would then send the key as a query string in the requests to google shown in mappress_api.php.
For those of us with Google Apps accounts, this key allows us 25,000 requests/day, and also gives us “analytics” to show how our visitors are using the map.