I purchased a three user license and installed it on three computers one being my daughter's. There are two user accounts on the computer and when her husband signs in he is not allowed to scan and purge infected files because it shows as "Unregistered".

How do I fix this? I tried having him enter the User Code and Serial Number but it said that the serial number is invalid which I know is not true because it works fine on the other two computers and on my daughter's sign-in.