Owners of the DRM-free version of No Man’s Sky, which can only be purchased at GOG.com, will not be gaining access to the multiplayer features that have just been added in No Man’s Sky NEXT update until later this year.
In a joint statement on the GOG.com forums, GOG and No Man’s Sky developer Hello Games explained that while “the DRM-free edition of No Man’s Sky will include all single-player content introduced by NEXT: third-person mode, upgraded visuals, better base building, player customization, and more,” multiplayer will not be ready at launch.
Source: IGN.com No Man's Sky Multiplayer Unavailable on DRM-Free GOG Version Until Later This Year