Title said all. I have both steam version and gog version, but bought the steam version first, and downloaded that version. Now that I have the gog license, is there any way to convert the steam version files to gog?

Because gog obviously won't recognize the folder. Maybe somekind of registry entry to fool galaxy client that I have installed the gog version and I can verify/repair from there and replace the steam dependent file with the gog version?

Consider redownloading a whole 8 gigs isn't an option., because I have very limited internet quota atm.

Thanks in advance.

No, you can't convert them, they're two separate and fundamentally independent builds. You'll probably find the player base on the GOG version is exceptionally lower compared to those on the Steam version anyway.

Nah I don't really care about multiplayer/online.

I just want the DRM free version.

If you want the DRM free version (which isn't different in any way to the Steam build in any case), then purchase and download the GOG.com version. Steam's version can not, in any way, be converted. And if you did do that, it would probably be considered illegal per Valve's TOS.