Upgrade NIS 2010-> 2011 with a 2009 license

Hi .

I have now installed NIS 2010 and i want to upgrade to 2011 ,but the license i have is from a 2009 version . Is that possible ?

If not...can i uninstall NIS 2010...install the 2009 version and then upgrade to 2011 ? ( all in all can i use the 2009 license ?)