You can now add a personal link to all of your stories, asking people to become paying Medium members. If they sign up through your link, you will get about half of their monthly fee in personal earnings..

I added one in my latest story. Go to the bottom of this article to see what I mean:

https://link.medium.com/6s20cQ8PTjb

You find your own link by clicking on your profile image, then settings and promote.. You have to state that it’s an affiliate link to be able to earn.