This should be very simple to do and simple to find either on the Logos FAQ etc. or the WIKI. Not! At least, I cannot find it.
There is the unsupported way to install L4 on a second computer but I cannot find the supported way. Is the following link current? Does it every change? All Logos said in their FAQ was to use the link provided in the email you receive after purchasing. And that was months ago...
http://downloads.logos.com/LBS4/LDLS4Installer/Logos4Setup.exe