In the era before Steam, the physical CD key—a sticker inside your game's jewel case—was your identity. It was your license to play, and online servers would check your key against a central database to ensure only one person was using it at a time.
It is important to distinguish which version of CS 1.3 you are trying to activate, as the keys are often not interchangeable.
The WON system was soon after shut down, and the era of manually entering a CD key for every install was over. Your unique WON ID was replaced by a Steam ID, but your digital library was now connected to your account forever.
In its original retail form, Counter-Strike was either a mod for Half-Life or part of the "Half-Life Platinum Collection".
With these details, I can provide the exact steps to get your retro CS setup running. Share public link
Counter-Strike 1.3 remains a pillar of gaming history. While official support and new CD key sales ceased decades ago, the community still maintains access to this foundational version for historical appreciation and LAN play.