Justin Sullivan/Getty Images
The company wants to create a club of special members who pay $5 a month.
In a blog post announcing the news, Medium said the membership will confer access to "a new layer of Medium."
The company provided few details about the membership benefits, but said that the site would remain free to those who are not members.
The move comes a few months after Williams publicly swore off advertising, denouncing the
Williams also abruptly laid one-third of Medium's staff in January as part of the change, angering some of the advertisers and publishers who had signed on.
"Medium will remain the best place to share ideas that matter and to find independent voices and fresh perspectives - for free," Williams said in a blog post on Wednesday. He said Medium would offer paid memberships to everyone in the next few weeks, but that it was currently only inviting members who "meet certain criteria."
For $5 a month, which Williams noted was an introductory price, Medium members will get exclusive stories, a "first look at newest reading features" as well as a special offline reading list.
"We need a system that funds stories and ideas not just based on their ability to attract attention, but on their value to readers. This is the system that Medium is building, and as a founding member, you'll get to help tell us what's most valuable and how we spend that money," Williams said in the post.
"Let's stop relying on ad buyers and social media echo chambers to determine what we put in our brains - which is just as important, or more so, than what we put in our bodies," Williams said.