Thank you for the email support link. I sent a ticket with my question about whether the update is for 5 installs or just one. It seems like a rather simple question that only requires that someone from stardock to post "yes" or "no".
I eventually found the license - it was not what appeared to be the license number that was first posted on my account. But the later posted license did work, so all that is left to know is whether that one license is good for five installs.