Whilst I don't know an easy way to do this, you could try - Submit a support ticket
https://support.avast.com/en-ww/contact/sales in your case select the Billing, payment, or license issues option - and then the I have a different billing or license issue and click Next and follow.
This I feel is possibly a way, however it is almost certainly going to ask for your order ID number, enter 00000000, that should at least give the opportunity to submit a ticket and give as mich information as you can to help them to find the actual order ID number.
You could also try this (possibly first) and see if it also sends you the order ID also.
- Resend avast License
https://www.avast.com/resend-license-paid.php, you will need to enter the email that you used when purchasing the license, e.g. the one that the original email with the link was sent.
