My dad and brother have the Garmin Rino 520 (??)
No, they don't have a monthly subscription. Don't know if there is an option for one, or what it gives you. I don't think there was any map preloaded. Just a layout for where you are, plot points and information of where your "friends" are.
My brother did purchase the maps.
The one they have allows you to see where your friends are (others with rinos) and also has a radio included. They love it.
The pulled them out of the box - did a quick study, then jumped in the trucks and played a game of hide and seek. Pretty decent range - a few miles between them.