|Do you mean if you install some software from a cd on one computer, can you install that same software on another PC using the same cd? If so, yes. The cd cannot be written to and therefore doesn't have any record of its previous usage.|
However, if it needs to ba activated by the website of the company supplying the software then likely they won't activate it the second time on the other PC. And many software companies tell you to only use it on one computer even if it doesn't need to be activated. Of course, they're not going to know if it's used more than once.
You're not really green until you're soylent green.