Is there a possibility that you made a typo on your email address ?
Or check your email spam folder in case it has ended up there.
You could try this to see if sales can track down your order - Submit a support ticket
https://support.avast.com/en-ww/contact/sales_other_general#pc -
Refunds, cancellations, billing, payment or license issues and click Next.
I need help with a different subscription or billing issue.
Depending on your location you can Phone or Email - I think the email option may be best as it establishes a support ticket with your email. Give as much information that you can to help track down your payment and reissue the license if it has gone to an incorrect email address.
Support tickets are handled on a First In First Out and can take between 5 and 10 working days, depending on payment method.