I purchased X3 Producer from the Cakewalk web store a few weeks ago but when I went to install it tonight I found I had no email from Cakewalk with the serial number (just a purchase confirmation email) and the serial number was not listed in my Cakewalk account.  That should have come in the email, right?
 
                               
 
Edit: My error.  I didn't notice there were multiple lines for the X3 purchase in My Account.  I found the serial number in another X3 purchase line.

Check your store account. All registration info should be there.

@scook,
 
The store account shows the purchase but no serial number.

Then it is customer support you will be contacting.

Make sure the serial number didn't go to your spam account.