This has been my experience with Sirius XM:
1. I had it in my 1986 Landcruiser and canceled it when I moved overseas in 2013. When I sold the LC in 2017, the satellite radio was still going strong.
2. I got 4 months free in my 2017 Subaru Outback. Once that expired I never responded to any of their mailers and told their sales rep on a phone call that I wasn't interested in continuing the subscription. They reactivated for three months for getting my car serviced at the dealership sometime in 2018. I sold that car (to buy my Tacoma) a couple of months ago and the satellite radio was still going strong.
3. On the other hand, my wife canceled her subscription when she sold her Jetta in 2013. She had it on autopay using a credit card that she stopped using once she canceled the subscription. Sirius continued to charge the card and we only found out when we started the house buying process and saw that her credit score was wrecked from have the card canceled due to nonpayment. There's obviously another lesson here about making sure mailing addresses are updated and checking your credit every so often, but to wrap it up I don't feel the least bit bad for getting free satellite radio on our other vehicles.