Why do my maps have a number of months behind them in Nav?

Is this the last time they were updated or how much time I time to use them until I have to pay for a subscription?

 

The subscription is for the entire nav system , not each state. I would guess and say, the number of months is how recent that particular map was last updated by them. Btw, the nav doesn't stop working after the subscription runs out, you just wont get anymore updates until you pay them

 

I think the months represent how long it's been since the map was updated on your bike.