One of the LW employees pointed out to me that the most common mistake (if true Pro users), is people forget which email address they registered Pro with. But if you still have the email then obviously you used correct email address.

Solution: Check the details of the Credit Card Receipt. Now see Upgrading to V 4.18 (click on link), below image see the point made at the asterix * ... that is where you can find your download page url address.