Can the NIS 2013 be installed from an upgrade disc?

Hi,

 

I have three computers, two of them have NIS 2012 and my license is ending quite soon so I've already purchased NIS 2013 upgrade disc that contains three licenses. The third PC doesn't yet have NIS installed in it but now I want to install that in it. Is it possible with the upgrade disc? Or do I have to download a complete version of NIS 2013 from somewhere? If I have to download a complete setup file, can you tell me, where it can be downloaded? Thanks a lot!