I use my Coin Organizer Deluxe on three different computers that's one thing I must have with any software I use.
Now you must install the software on all three systems but then it is easy with this simply copy the files to CD or any storage device and overwrite the old file.
I guess you could install the software to the external hard drive also. Also you can backup the files then just restore the new backup to any system. Going to copy the software to my external hard drive and see if that will work on all three systems should just add a shortcut to the desktop on each computer.
Or what I do is save the data files on my external hard drive then I use this hard drive on all three computers sharing the same data files.
I use an external hard drive to keep all my data on