Pay to Blog within Pro Sites- No Free option

Hi there! I am in the process of setting up Pro Sites and I would prefer not to offer a "Free" option to my customers. I read in a thread somewhere that I should enable the Pay to Blog Module within Pro Sites. My question is... do I need to also install the Pay to Blog plugin separately? Or is that plugin already included within the Pay to Blog Module that is built in to Pro Sites?

Thanks!
J*