NoMachine Workstation Subscription appears to be installed on this host. Two different NoMachine packages can’t be installed at the same time on the same host. Be sure you uninstall NoMachine Workstation Subscription before installing NoMachine.
and
http://download.nomachine.com/download/4.2/Linux/nomachine_4.2.26_1_x86_64.tar.gz
You can’t install NoMachine (the link shows the free version) on top of a Workstation (Production Version) as the message states. Install the Update Version of the Workstation on top of the Production Version of the Workstation, or completely remove the Workstation, including the license, and install the free version.
The Workstation is downloadable from your customer area. Log on to download it.