when you bought your truck the serious was an option.
it is listed on your option sheet.

 

I just got off the phone with Sirius to find out what to do. First they will ask you for your account # or your ESN or SIDS number so they can access your account. They have another option, your phone number, so if your Ford Dealer included this in your profile you will be ok. I found out my subscription won't expire until July so we agreed I would call them back in late June. I can extend an additional 6 mo. for $51.80, to 24 mo. for $181.30, and 36 mo. for$310.80. Hopes this helps.

 

From what i understand, sat radio providers have codes that they send out to your tuner to turn off or on.

Your tuners reciever id number is used for that purpose.
There is a rumor on another forum that XM sends out the signal to turn off your tuner after your subscription is up and the tuner will then not activate.
Im sure sirius is the same. Apperently if your tuner isnt powered up, it cant recieve a "turn off" signal. Meaning that next time its connected it is still operable. From that, there have been users that disconnect the tuner before their subscription is about to be up. When the sat sends the turn off signal, it doesnt recieve it cause it has no power. Then a time later, they connect it back up and stil have service. The only drawback is that the sat provider randomly sends out the turn off signals to the units that are supposed to be off. But ive heard of guys getting as little as a week extra to up to a few months extra.

Dont qoute me on that as its a rumor, but needless to say, my tuner is currently disconnected. maybe in three months ill hook it back up and see if it still works.