Its because when you install the program, it adds registry entries to the registry, when you copy the folder you arnt getting the registries. There may also be some files that are in the "system" folder on the downstairs computer.
Unless you want to go searching throught the registry and system folder to find annd the bits and pieces, you will probably have to install it on the upstairs computer from a CD. And if you bought it, you should have the CD.