Log into your magix account and look under "my products". If you don't see it there, contact magix support. This isn't official support, but rather a user forum, we're all just fellow VEGAS users here, and this is an issue you need to contact Magix directly about.
If there's nothing there, try contacting shop@magix.net
"If you have not received the confirmation email, please contact our customer support, specifying your order number, under: shop@magix.net" (from the "Thank you for your order" document from MAGIX)