This can actually be ignored.
The LimeLight CDN is being phased out, and it actually out of rotation in the mCDN. You only need to worry about it if you have the old page code which referenced Limelight on your site.
So every account will try to publish to Limelight, however not every account will use it.
Even though you get the error and the extension is marked "not saved", that's not techinally true. As the save will happen before the publish.
We are in the process of removing the Limelight publish code (and errors) so this will no longer be an issue.
If you want to verify that what you have published has gone out, I would check the CDN URL: