serial Number

I bought democracy 1 from an Charity shop near me. I Think it would play on my infernally slow laptop. The serial number was not in the box. Im pretty sure its a legit version as its properly printed on cd and game sleave is printed on glossy paper. Is there anyway i can get a serial number for this. I dont mind sending it back and if its a legit version send me it back with a serial or what ever. anyhelp would be great