This live label is reserved for publishers who have implemented the brand new live blogs schema structured markup on their sites. It will show up in the publisher carousel when Google finds it to be relevant.
Here is a GIF from Google showing it off:
You can likely see it yourself if you go on your mobile device and search for [abdelhamid abaaoud] since there is breaking news on it now.
Again, if you want it, add the structured markup and make sure you have live bloggers on hand for your site.
Forum discussion at Google+.