Sounds like what Vistaprint (online stationers) did. Bought some notepads from them and unwittingly bought into some purchasing with 3 months "free use". They don't immediately charge the credit card or email/mailed materials letting you know you've "joined" the Club. Three months later you start getting charged $20/month from some company in Virginia. If you don't look carefully at your monthly invoice, you'll miss it. Bastards.