Companies that are creating an implementation of the Remote Desktop Protocol set can license the Intellectual Property(IP) rights they need from Microsoft by signing the RDP Client License. Products that might need these rights to interact with Windows Remote Desktop Servers (Sessions or VM based) include:
To understand if you might need the patent rights associated with the protocols, Microsoft has also published a map of which patents are associated with each protocol.
The copyrighted documentation for the protocols has been available for free on MSDN for over two years:
To learn more about the license and other benefits of being a licensee, please contact email@example.com.
In addition to receiving a license to the patent rights you need, companies that have taken the RDP Client license will also enjoy: