For the past decade, publishers have utilized metered paywalls to grow their subscription businesses. Under that model, a reader gets to view a certain number of free articles before a paywall pops up and requires them to subscribe.

But how many free articles should a user encounter before they hit a paywall?

Increasingly, the answer to that question is: It depends. Publishers are starting to roll out dynamic paywalls that assign varying weights to different kinds of stories. If you're reading a business article, for instance, you may only get to read three free articles before hitting a paywall, but if you're perusing real estate listings you might get unlimited free access.

The Globe and Mail has taken the idea of the dynamic paywall to the next level: it's developed a sophisticated AI that's able to analyze user behavior and determine the exact moment that a reader is most likely to subscribe. The AI is so powerful that the newspaper's editors now allow it to automate the placement of stories on its homepage and social media.

I recently sat down with Gordon Edall, the person who runs the product team that developed the AI. We talked about how the paywall was initially designed, his experience recruiting data scientists, and why the Globe and Mail is licensing its AI product to other publishers.