I have my swat 4 key, but can I redeem it here on GOG? I dont want to buy it again. you feel me.

If you mean a retail box key, it doesn't work that way unfortunately. There was a short-lived, promising, system a couple of years ago where gog allowed to to redeem a bouple of games from the boxed version codes, but we haven't heard of it anymore. And there's the occasionnal "connect", which allows some steam games to be activated here, but again, it's just selected games, during a short window.

The videogame industry is mostly about re-buying your game if you want it on another online library/shop.

That suck because I already have it when it's the same game and codes. That's wrong. Thank you tho.

Heh, we're all in the same situation with different games.

Sometimes we just re-buy them, when they're discounted dirt cheap. It's like paying a little extra for having them "dematerialized" and kept updated for modern systems. As if you were paying a garage to change the oil in your old game, but only once.

You have the key, do you not still have the CD?

1º Error, CD KEY, SERIAL, NUMERO DE SERIE.
Cuando quieres iniciar un servidor/dedicado desde el menu del propio juego.
--Este error se genera, por que no estan los seiales, bien, puestos en la ruta del registro.
Equipo\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Sierra\CDKeys

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Estos se pueden agregar creando un archivo *.reg
Archivo REG 64bit
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Sierra\CDKeys]
"swat4"=hex(3):67,9E,27,86,B9,83,10,77,AC,09,7C,6D,6B,5D,D6,70
[HKEY_LOCAL_MACHINE\SOFTWARE\Sierra\CDKeys]
"swat4xp1"=hex(3):B7,4B,8C,09,84,8C,9B,50,B4,B8,BA,93,C6,20,F6,CD

Ejemplo del registro
NYD2-MAB8-REJ3-MYM6-4733
67 9E 27 86 B9 83 10 77 AC 09 7C 6D 6B 5D D6 70

XAX7-JEM3-FAT9-MYM9-7782
B7 4B 8C 09 84 8C 9B 50 B4 B8 BA 93 C6 20 F6 CD

¿Como puedo sacar mi archivo reg de mi KEY/SERIAL?
Use un CD de instalación dale e instalar, y cuando te pida el Serial, Escriba el tuyo.
Dale 1 vez a siguiente.
Ahora valla a la dirección del registro.
--64bit
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Sierra\CDKeys]
--32bit
[HKEY_LOCAL_MACHINE\SOFTWARE\Sierra\CDKeys]

Haga clip derecho encima de ejm: swat4 y dale a exportar.
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Necro alert!

Looks like the OP didn't bother with GOG anymore, after he found out (three and a half years ago!) that his CD keys would not be accepted...

shrug