Not sure why the licensing question came up. It was free back then, so I don't know why it wouldn't be now, unless Bell Labs revoked the previous license.
More than anything I was trying to figure out the last release date. I've got a plan9.9gz file dated 20010327, and some odd patch files, the largest of which is 10140327.9gz dated Oct14, but I'm not sure if that's October 2000 or October 2001. Was hoping to hear if anyone had anything newer. Anyway, no worries... just fact-finding. Many thanks!! -Ben