lost activation key for free em client

my boyfriend has been using em client free since 2014.  a few days ago he told me he was prompted to reregister so he tried to do this and was sent a lost activation key.  at that point his em client email deleted all his saved mail but when either of us try to enter his new activation key (following the prompts to go to help/license) there is no way to enter new key and it seems that his license is already current.  I am not familiar with either windows operating systems or em client but i am slightly better with computers than he is so I am (sadly) the IT person in our household.  Please help!!  His email address is different than the one I used to sign up to ask this question so if someone from em client is trying to look at his account using my email it won’t be possible.