If you have placed an order and the payment has been taken successfully then the email containing your digital product key may have ended up in your spam / junk mail.
If you purchased using PayPal then check the email used to login to your PayPal account.
Another possibility would be that the email address was entered incorrectly. If you didn’t receive a confirmation email after a successful checkout then most likely an incorrect email was used during checkout. Please submit a ticket to resolve the issue.