The USB Rockey hardware key (dongle) is used as an alternative to node locked (Ether ID) licenses. You can use a single dongle on any number of systems.

On Windows and Mac OS X systems, no special driver or device setup is required; you just plug the dongle into a spare USB port and the headus licensing system should find it.

On Linux systems though, you may need to adjust the usb device permissions to allow the headus licensing system full access to the dongle.

Unplug the dongle if you have it plugged in, then type this ...
  ls -l /dev/bus/usb/*/*
It should show something like this ...
crw-r--r-- 1 root root 189,   0 Sep 29 14:35 /dev/bus/usb/001/001
crw-r--r-- 1 root root 189,  49 Oct 12 09:31 /dev/bus/usb/001/050
crw-r--r-- 1 root root 189,  50 Oct 12 09:31 /dev/bus/usb/001/051
crw-r--r-- 1 root root 189, 128 Sep 29 14:35 /dev/bus/usb/002/001
... though the exact number of devices and ids displayed will vary 
from system to system.
Next, do this ...
  ls -l /dev/bus/usb/*/* > usb1.log
... then plug the dongle in, wait a few seconds, then do this ...
  ls -l /dev/bus/usb/*/* > usb2.log
... then do this ...
  diff usb1.log usb2.log
You should get a single line which is the device of the plugged 
in dongle.
By default the permissions on that device may be "rw-r--r--", 
but you need "rw" across the board, so as root, do this ...
  chmod 666 /dev/bus/usb/whatever
... replacing "whatever" with the device id that the diff 
command finds.
Run UVLayout and the dongle should now show up in the licensing
GUI and UVLayout will run once you edit the keys file.
To make the permission change permanent, you will need to create
a new Udev rule. As root, do this ...
  cd /etc/udev/rules.d
  cat > 49-rockey2.rules
Sometimes that doesn't change the permissions, but will the group, 
so just make sure that users wanting to use the dongle are in 
the "users" group.

Note: Under Ubuntu 13, Centos 7 and possibly other distros,
change "SYSFS" above to "ATTRS", otherwise everything else works
as descibed.