Look for the serial number on the back of the CD/DVD case, on a sticker inside the case, or on the front page of the printed manual.
Review the email sent to you after your purchase; serial numbers (e.g., starting with "ATS9" for older versions like TS2009) are often included there. Serial Number For Trainz Simulator Hd
Check the My Digital Downloads page in your MyTrainz account. Your serial number and download link will be listed under the appropriate item. Look for the serial number on the back
To authorize your game and gain access to the Download Station (DLS) or forums: on a sticker inside the case