It will read your serial key from the registry and just work. That means that if you already have the GOG or Steam version installed, you can download any Retail version of Mount & Blade: Warband from ftp//ftp.taleworldscom and install it to a different folder on your computer. If you have the GOG version of Mount & Blade: Warband, it should work like the Steam version and write your serial key to the registry. I do not have the GOG version, so do not ask. I may be able to modify it to work with that version.
Test it and let me know if it doesn't work with the version you want to use it with. I know some people like to use previous versions for Mod compatibility. Now updated for v1.168 (Should work with some other versions.
