Going to clarify a few things and answer a few of the questions from above:
It should be noted that Manage UI doesn't have any features that cannot be accomplished from
chef-server-ctl. Checking out the documentation for knife would be the best bet to see what is available. ManageUI is just a visual representation of the chef-server data and it effectively acts as an API client to chef-server. It has no information of it's own so to speak and is not necessary for running chef-server.
For any other commercial products, they are denoted as commercial on the documentation pages and when you actually go to download/install there is an MLSA (Master Services Licensing Agreement) you must acknowledge. I know folks often click through EULA's like that but that actually includes the legal rules on use.
As stated, there is ONE license currently which gets you access to the entire suite of commercial products which includes: Automate (Visibility/Workflow), Compliance, any of the chef-server plugins (reporting, chef-sync, manageUI), and support. There is no way to buy individual products or components, especially given that eventually ManageUI and Reporting will cease to exist once they have been supplanted by other pieces of the Automate stack. All the OSS projects Chef supports or is connected to are nicely listed here http://chef.github.io/. As a rule of thumb, if the repo isn't public for a thing it's almost definitely not free or OSS. Also looking at our downloads page one can see that the downloads are broken up by OSS, Automate, and Premium (Legacy) and when clicking on download for non-OSS things you are prompted for information and as well as agreement to the Terms of Service and Master License Agreement.
Hope that clear it up some.