Pirate installer with key (Battlefield: Bad Company 2)

Here, actually, there was a problem. About three years ago I bought a disk with BC2 at the collapse (the Internet was then bad), but the pirates behind some banana shoved a number (!) For the installer - until you enter the number, the game will not be installed. And then sadness came - I lost the cardboard box. Two questions - has anyone come across this and does anyone know this nasty number?