If you have a legitimate copy but lost your code, you don't necessarily have to buy the game again. You can reach out to the official team. Provide them with a photo of your physical disk/case or a digital screenshot of your purchase invoice. They are usually able to verify your ownership and issue a replacement key for the 2013 edition.
: Para copias físicas, el código de activación se encuentra impreso en una etiqueta dentro de la caja del DVD. Archivo de Activación Local If you have a legitimate copy but lost
Si no posees una clave, puedes adquirirla en tiendas oficiales o comparadores de precios confiables: Farming simulator 2013 activation steam :: Off Topic If you have a legitimate copy but lost
If you have a legitimate code but it's not working: If you have a legitimate copy but lost