User blog comment:Simant/CC-BY-SA 3.0 - On Wikis/@comment-1417834-20140319005024/@comment-5175866-20140324171710

The reason why Memory alpha had a CC-NC-SA license is because they weren't originally from wikia, and when they moved over Wikia let them keep their license as well as their domain. Other wikis like LyricWiki have copyright mixed in with CC-BY-SA because the way LyricWiki is Wikia spends a lot of time on licensining for LyricWiki. There are other wikis within wikia that have moved and kept the license they started out with.