Steam DRM Not Working

Steam UE4 Built-In Plugins enabled. In DefaultEngine.ini, under [OnlineSubsystemSteam], I have:

bRelaunchInSteam=true (in addition to the other lines controlling other Steam functions)

Expected result: When the game is launched while not being connected to Steam, it will close and attempt to load Steam and load through the Steam interface.

Actual result: Game works normally while not connected to Steam.

You need to use the Steam SDK to DRM the EXE. Did you do that?