TeenVogue Fake Promise?

I got a letter in the mail from TeenVogue saying that I'm eligable for a free year subsciption, and a free checkered tote bag. The letter looks pretty real, and I was actually thinking about doing it since it's free. It also says that you could do two years for $10 instead of $59.80. I asked my mom if I could do it and she said no because "Nothing's ever free." Has anyone who's done this got it for ten bucks, or for free with no problem?