DavidR
2
You can use the Resend avast License http://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.
If you still have the license that you received when you purchased, if you can find it, save it to a USB stick, etc. and you can use that, otherwise the above is fine.