Yes, exactly right. In the blue menu at the top of this web page, you will find a link entitled "Planet Auran". Click that to visit your account profile. On the left side of your profile, under the "Trainz" category, is a section entitled "Serial Number". Click to that section. Now on the right, you will see an area to enter each product's serial number. Be sure to select the correct product for the serial number, or your entry will be rejected. Your serial numbers that have already been accepted will show up at the bottom.
This process lets our online systems know about your purchases. You've obviously experienced this before with the Trainz products, because the banner under your forum name shows a whole slew of registered products

Our payware DLC is exactly the same. kind regards, chris