Yes, but they’re still selling a revocable license, whether California law compels them to declare so plainly or merely in their shrinkwrap terms:

> 2.1 We give you and other GOG users the personal right (known legally as a 'license') to use GOG services and to download, access and/or stream (depending on the content) and use GOG content. This license is for your personal use. We can stop or suspend this license in some situations, which are explained later on.

> 17.2. Our right to terminate the Agreement. If you materially breach this Agreement, we reserve the right to suspend or cancel your access to GOG services and GOG content.

That they have provided you an installer is interesting but not legally relevant; if they revoke your license, your use of the installer is unlicensed and therefore, in theory, prosecutable. (This is of course difficult to enforce, but that’s only relevant if it’s theoretically prosecutable.)