Welcome to Trainz Unforsakin!
It is actually interesting that no one has mentioned this yet , but it is recommended that you register your Trainz serial number (a. k. a. CD key) for the Trainz versions that you own. The Trainz versions that you have registered thus will be displayed next to your username here on the forums, which helps other members by showing them what versions of Trainz you have, which may be helpful in answering support questions that you may ask in the future, and which also is your public proof-of-purchase that you have a legitimately-obtained version of Trainz. It also permanently associates your Trainz serial numbers with your account. To register your serial numbers, click the "Serial Number" button near the top of this page to the left (edit: slightly to the left, that is ), and register the serial number for each of your Trainz versions.
Kind regards,
Retro00064.