It does.... Just don't cancel the service and put it in a new tablet quickly and should be no issueI think it follows your SIM on an iPad.
Keep that and place it in your next/new iPad.
Then you sold your unlimited data plan. That SIM card was your key.
Those SIM cards sell for about $1000 by themselves on eBay.
It's not a loss yet! The owner of your iPad doesn't have your log in info for your acct. so he/she can't change it over to his/her name and lock you out. So just activate your new iPad w/ your unlimited plan (you don't need your old SIM) you'll be fine. It will automatically disable the Sim in your previous Air.