Microsoft's been in dispute with N-Computing since a long time ago, because this item can substitute a CPU without having to buy another copy of Windows.

Sometime later though, I think Microsoft won the case on the court, because N-Computing started removing their Q&A that stated that using their product would not make companies subject to copyright infringement by Microsoft, and started posting something like 'Must buy Windows <input type and version here> to use N-Computing'.

In October 2014 Microsoft enforce this through their Windows Update. If the main computer's Windows is updated, N-Computing will kick out any non-license-paying users.

The solution? Do not install the update starting from October 2014 and beyond! If it's already done, roll back using System Restore to any date before October 2014.