Zuckerberg wrote in a post [1] that the company is working on enabling subscriptions on the platform, and will start testing the feature with a small group of US and European publishers later this year, Mashable reported [2].
The new system will support both paywall (fixed number of articles) and freemium (locked articles) models, with Facebook prompting readers to subscribe in order to read more. Payments will be processed directly via publishers’ websites, who will also receive all of the revenue.
The Verge points out [3] that after trying Instant Articles, many big publishers have started to abandon them, but the new subscription tools could entice them into coming back.