Facebook Instant Articles : Why You Won't See A Like Button For Your Facebook Page In The Header

Facebook only displays the Page Like button in the header of a Facebook Instant Article when the reader has not already liked (i.e. followed) the associated Page.

When the reader already follows the Page, the Like button does not appear.

If you or members of your team are not seeing the Page Like button on your articles, it’s probably because you already like your own Page.