This probably should have gone in its own new topic, given that this topic is almost a year old and is likely different to your issue.
I suspect you are talking about Avast Pro, AIS or Premier license.
If so. save your copy of the avast license file to a USB, etc. and use it again when you install avast on the new system. Uninstall avast of the laptop if possible, if not don’t worry.
You can use the 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.
Once Installed on the new system, apply the license file as you did before.