Technically, the suite is not a separate product. It's a bundle of several other products (hence there's no general documentation for the suite - just for the individual products it contains [even though the documentation is rather weak, especially for the server part
]).
The SBS suite contains protection for the clients - so you don't to buy any extra Pro licenses.
http://www.avast.com/eng/sbs_suite.htmlGenerally, if you have any licensing questions, it's best to contact our sales staff at sales@avast.com.
Cheers
Vlk