It looks like authors have been able to opt-in to the paywall since late 2017: http://www.niemanlab.org/2017/10/starting-today-anyone-who-publishes-something-o

It looks like authors have been able to opt-in to the paywall since late 2017: http://www.niemanlab.org/2017/10/starting-today-anyone-who-publishes-something-on-medium-can-paywall-it/ http://www.niemanlab.org/2017/10/starting-today-anyone-who-p... But I think this is the first paywalled Medium article I've actually seen (and I think it was free when I came across it on r/math a few days ago)... but I've developed a bit of a reflexive avoidance of Medium content anyway.