Hello.
I have a new computer, how do I change my license (Avast I. Security) from old computer to new computer?
Uninstall from the old system, open your my.avast.com account and delete the device from there.
Install on your new system, use your existing license file, if you haven’t saved it - 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.
License file can be downloaded through your avast account