update: microsoft finally posted a kb article on this problem with full detail called Unable to import a license into the Opalis Integration Server License Manager.
while importing license keys, this warning might be a little surprising since as far as i know, we’re way beyond 12/30/1899.
luckily the opalis knowledgebase still works. in my case, i got this error message because i was trying to import the license key from a unc path. once i moved it to the management server, the license key imported just fine. :) there are other reasons though probably not as likely.
here’s the full article titled “unable to import license into opalis integration server license manager”.