Medium saw impressive growth last year as it shifted focus from independent writers to established brands like The Awl, Think Progress, and The Ringer. Readership and published posts were up approximately 300 percent last year. But the company also struggled financially. It eliminated 50 jobs last month and closed down offices in New York and DC. At the time, Williams claimed advertising-focused business models aren't serving content makers or consumers.

He added, "The current system causes increasing amounts of misinformation...and pressure to put out more content more cheaply — depth, originality, or quality be damned. It's unsustainable and unsatisfying for producers and consumers alike ... We need a new model."

A subscription-based service is obviously Medium's first step toward finding a new model. If successful, it'll provide an additional source of revenue to the struggling blogging platform.