It's like Clifford said, the first shipment contains free pieces, and premium pieces. If you don't want to continue the subscription, you can cancel it, and send the premium piece back to them. You get to keep the free pieces, though, either way. You are going to want to stay subscribed, though, because it's the premium pieces that are really nice

They give you free pieces, as part of the introductory trial, but then a subscription kicks-in.
It's pretty cheap, though, considering the quality of what you get...