Companies creating an implementation of Remote Desktop Protocol set can license Intellectual Property rights they need from Microsoft by signing RDP Client License. Products that might need these rights to interact with Windows Remote Desktop Servers (Sessions or VM based) include: Non-Windows Thin Client devices; Non-Windows based client software. To understand if you might need patent rights associated with protocols, Microsoft published a map of which patents are associated with each protocol. Copyrighted documentation for protocols has been available for free on MSDN for over two years. In addition to receiving a license to patent rights you need, companies that've taken RDP Client license will also enjoy:
"Free documentation support via community forums. Free attendance at protocol plugfest events: quarterly meetings where attendees receive presentations about specific area of protocol technology and have chance to interact directly with Microsoft engineers. Network Monitoring (NetMon) tool, that allows you to capture network traffic, view & analyze it. Microsoft has begun releasing test suites for different protocols and will continue to roll them out over time. Microsoft will shortly be making available reference source code for an implementation of RDP 7.1 only to RDP Client licensees," writes Microsoft.