Weirdly, Steam doesn't get enough credit for being DRM-free for many of its games; games that don't ship their own DRM or use Steam CEG are effectively as DRM-free as GoG games are. You can't transfer them out of your account, but you could zip up the folder they reside in and copy it to another machine without problems.
The Steam executable itself is a DRM system, as far as I am aware there is no way to download via the website as there is with GOG (or Humble's DRM free options or other DRM-free sites), so personally I don't consider Steam ever DRM-free.
Weirdly, Steam doesn't get enough credit for being DRM-free for many of its games; games that don't ship their own DRM or use Steam CEG are effectively as DRM-free as GoG games are. You can't transfer them out of your account, but you could zip up the folder they reside in and copy it to another machine without problems.