ED should seriously consider updating the Steam product pages to account for the new situation.
I didn't buy several aircraft modules during the recent sale solely because I didn't want to deal with the annoying and customer-unfriendly limited activation DRM scheme.
Besides, the following text can be found in the steam description of the Argo campaign (maybe others, I didn't bother to check), and if it isn't true anymore, ED might also want to change it:
Please note that this DLC uses Steam Keys instead of Starforce keys. As such, this purchase cannot be activated on the DCS World e-Shop version.