In the case of transfer of ownership there's little GOG can do (legally) except lobby. But from a technical standpoint access to the games is guaranteed by the

In the case of transfer of ownership there's little GOG can do (legally) except lobby. But from a technical standpoint access to the games is guaranteed by the DRM-free part. You can have the binaries free of encumbrances, effectively owning the game (binary). Possession is nine-tenths of the law.