Last time I got a free sub to one of the ZDMirc's I opted for the digital (big mistake, it just ain't the same as the good ol' paper copy, and that coming from a real geek) and I just kept deleting the notifications in my inbox and forgot I had the sub. My dad started wondering where these bills from pcmag were coming from and I couldn't remember. So I checked my junk folder a while later and found all the notifications, they were still sending the magazine, but because there wasn't a way to tell them I wanted to go back to print I'd complete forgotten about them, and so I went ahead and just told them to unsubscribe me...
All that to say, yea they bill, but they don't stop sending just because you don't pay, and opt for the solid paper version, it's much better