How can I find it..
My friend forgot his pw and want to restore account its asking for the product ID..
It's in the game, I can't make a screenshot of it, but it's where the information about the game is showed in the window, telling you your current version of the game among other things.
After all... 

Sorry for double-posting, but cansomeone actually make a screenshot to show @medinos
? I guess that'd be more helpful.medinos wrote:notification
After all... 

Open the game, go to Help&Tools->About. The Product ID is on the bottom.