You can install and use the software on 1 computer at a time.   When you install the software onto another computer and input the license number it will ask if you want to transfer the license.  If you say yes you will then remove the license from the 1st computer.  Making the 1st computer needing to be registered again.  The license number will allow you to transfer up to five times and after the fifth time it will not allow you to open the software any more.  If you are no longer able to open your software or you are wanting to install the software on more than 1 computer at a time, you will need to purchase another license number or more than one copy of the software.  You can contact Pazzles Sales Department for more inforamtion (866)729-9537.