EV mailbox license challenges

Hi 
I am looking for a guidance to know appropriate number of licensed users of EV for mailbox archive. I am fine using usage summary report OR anything from logs (e.g. IIS) / SQL/PowerShell. Please apologies however I am not confident enough if Veritas tool (EVLA..ETC) gives correct picture of licensing. For any legal OR licensing perspective, this is very difficult to find out who is the actual user for EV. 

Here is my thought. 
•    Mailbox archive by EV when it used to exist in exchange servers. Now if mailbox moved to EXO however, he may OR may not access the archive depending upon usage. For e.g. he may access EV for 1-2 month or maximum a year. Now since one-year emails are being archived by EXO then it’s rare user will look into EV archive. This situation AD a/c still exist. This may not reflect actual EV licensed user. Additionally, organisation pay double archiving fees as one is EXO second for legacy EV archived emails . 
•    User left organisation and his EV archive still exist.  For any reason say for example, retrieving important email, permission is assigned to his manager then again this will be eligible for license. 
•    A shared mailbox archive either inactive or active, permission is granted to team members then the all-group member will be eligible for license. 

In my opinion, the license should be there only for a mailbox that is active in on-premises and archived by EV. All AD user account of shouldn’t be eligible for license. There could be best practice such as below. 

•    Mark in-active archives. E.g. User is migrated to EXO or left OR where there is no need to access to old, archived emails. 
  •    Remove permission from archive those are marked as in-active. This is good options instead of deleting archive. 
  •    Remove unnecessary permission archives from shared mailbox OR user left from mailbox. 

Please help me if anyone have similar challenges and have better high-level plan. 

Regards
Pradeep Papnai