I was told something different when talking to the already useless uconnect customer service. So i guess i should take it with a grain of salt. It was explained to me that you have to have a UConnect access account setup in order to link the apps to the car. The Subscription is different, it allows for the "keyfob" on the phone to work, the vehicle status updates, the bells and whistles if you will. The Via Mobile functionality will remain in tact even without a subscription.
I tested this theory in part with a friends GC. My wife has a UConnect Access account linked to her iPhone that has the Pac assigned to it. She can use the "key fob" on the phone and via mobile apps. I have a separate UConnect Access account linked to my iPhone that has no car assigned to it. I have via mobile apps working (no trial, no subscription). I can go into my friends GC and link to Bluetooth, turn his BT off so his phone doesnt take priority, and still access my via mobile apps through his stereo.