Facebook "Like-gating" refers to the practice of forcing Facebook users to like a profiler page in order to see additional content.
Techopedia explains Facebook Like-Gating
Previously, some marketers and other promoters resorted to the practice of setting up Facebook profiles that required users to first "like" the business or organization on Facebook before proceeding. To encourage users to do so, incentives were provided including Facebook Like-gating contests, coupons or other opportunities.
As of November 2014, Facebook reengineered the site to disallow the function of Facebook Like-gating. Businesses and other page owners can still ask visitors to "like" them on Facebook, but they cannot hide Facebook Like-gated contents away behind a virtual wall.
The move toward banning Facebook Like-gating promotes openness in Web communications and forces profiles to acquire Facebook "likes" through organic and natural user choices, not through incentives.