temporary 4th user KEY for NIS2011

I have a 3-user NIS2011.  However, I have just ordered a new computer to replace my own, and I have already used up all three keys (one for my current computer, one for my wife's, and the third for my son's).  I need to protect both my current computer and my new one until I get all the programs installed and the data transferred over to the new computer.  Once that is done, I can uninstall NIS from the old computer and use that key for the new one.  But what would be the best thing to do in the meantime?  I am not willing to connect my new computer to the internet without protection, but also will need the old one for at least a few days, until I'm completely installed on the new one.  Is there a way to get a temporary 4th key?  Or should I install the 30-day trial version of NIS2012 on the new computer until I am able to uninstall on the old one?  If I do that, will the NIS2012 trial version conflict with my current version (2011) when I try to register it with my key?  Thanks for your help.