How do I stop receiving Bicycling Magazine?

A few years ago I briefly subscribed to Bicycling Magazine. I don't think I paid for it; it was some sort of freebie from my credit card company or something like that. Anyway, I quickly came to the conclusion that it's primary purpose was to induce me to shell out for new gear and declined to renew my subscription. Despite that I continue to receive copies on semi-regular basis, complete with the requisite occasional threats about how if I don't pay up I'll stop getting them. Empty threats, apparently, since it's been years now. This makes me wonder, exactly what do I have to do to stop getting the magazine? I realize that the business of magazine publication is primarily advertisement, but don't the advertisers want any evidence at all that people actually subscribe voluntarily?