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GOG version of SpaceChem doesn't require additional key.

Did you run both the installer and the game executable as administrator?
andrewwo: Same here, using XP on administrator account.
Installer prompts Microsoft .NET Framework download and installation. With this uninstalled the game will not launch. With it installed the game launches and then requests 'Spacechem Key'.
Did you have any previous version of Spacechem installed on that PC before?
We're trying to replicate the issue but with no luck do far.
The issue was addressed in new build ( if it's not already on servers, it will be shortly.

IF you experience problems with key authentication, please uninstall current version and redownload the game.