Patch 1.5.0 focused primarily on final stability and performance refinements:
Due to technical issues at launch, Ubisoft made the "Dead Kings" DLC free for all players permanently and offered a free game to Season Pass holders as an apology. Update 1.5.0 Key Features Assassin’s Creed Unity Free Download (v1.5.0 & ...
Legitimate free access to the full game occurred during a specific window: Patch 1