A few years ago I had a Sirius radio installed in my van. The shop installed it, but I had to call Sirius with my credit card handy to activate the subscription, before I did that, no Sirius. So far, so good.
Today I had a Sirius radio installed in a different car. The installer had asked me if I wanted them to activate the Sirius account for me, but I declined. I had a 2-months-free offer that had come in the mail, so I tucked it in my purse, intending to activate in the parking lot right away after the install.
But when I picked up the car, the installer said that when he fired up the radio, Sirius was already active. 
He called them to ask about it, and they didn’t have an answer. I said I was surprised they didn’t ask him for the serial number so they could deactivate it, and he said he did give it to them, but they didn’t do anything with it. Sure enough, when I went out to the car, boom, I had Sirius in all its glory.
Anybody know what’s up with this? I had a similarly confusing conversation with my vet’s wife a few weeks ago, when she told me that they have satellite radio in one of their vehicles (she couldn’t remember whether it was Sirius or XM) that they’re not paying for. The only explanation that I could come up with was that it’s a used car, and maybe the previous owner had paid for a lifetime subscription. But that doesn’t explain why I have free Sirius on a NEW radio.
The installer did say that their store radios have some sort of “demo” subscription, but this was a new radio fresh out of the box.