I have an old unit that I tried using after I cancelled years ago. I waited 3 months like someone told me, turned it on, and sure enough it worked. Not for long, maybe a couple weeks? I forget. I tried it a couple months ago again, and no dice. Will give it a try again soon.
I have a 2014 GM vehicle and let my free 3 months lapse. I had a problem with the electronics for a short time, where the backup camera stuck on. It cleared up, but after that, the SiriusXM started working again! It went in for repair, and they did an update on the radio system, and the SiriusXM stopped again. Oh well, not a big deal to me.
Authorized Service Provider (Contractor) for MTS Allstream. Any views expressed are my own.