Switching computers

I want to give my netbook to my son to replace a malfunctioning laptop. I have a couple of questions concerning the NIS Product Keys:

 

1) If my son chooses "Renew Subscription" and enters his own Product Key, will that automatically "free up" one installation for my Product Key?

 

2) If my son disposes of his laptop, how does he "remove" his Product Key from it to "free up" the installation for use on another computer?

 

Thanks