Broken License for Photoshop CS3

I have a very old version of Photoshop CS3, which I acquired before retiring from the IT Department of  local college a long time ago.  Let week when I tried to open the program I got a message informing me that my license was broken.  I no longer have the CS3 disk.  All I can find is an old Photoshop 5 disk.  I have the Password for that but it is not accepted.  Any help appreciaitd