NIS 2010 3pc license usage question

Hi All,

 

Can someone please explain how the 3pc lic works? If I have only two pc's in my house and one license is left over,  can I give it to someone else or sell it? Or do all licenses require the same IP address?

 

Also, in the event I keep the extra license, how long can I hold onto it before it expires...if in fact it even does expire? And when I do decide to activate it, it still becomes active for a year from the activation date correct?

Any info would be appreciated, thanks.