Licence file doesn't work

My father has a 3-machine licence for Avast and Avast is running on each machine. He has renewed and paid for his subscription, but only one machine has updated. Attempting to install a licence file results in ‘Invalid’

How do we update the other 2 machines?

Should be simple enough as inserting the license key

https://www.avast.com/faq.php?article=AVKB7

if you have trouble, try contacting avast support.

https://www.avast.com/resend-license-paid.php
https://www.avast.com/support

Already tried that several times…

Requested the licence file several times, doesn’t make a difference. Also, the device can’t be added to the account (even though it’s been using the licence OK for 3 years)

Did you removed the devices from your account before trying to use the license file ?