Does anyone have a process to disable O365 mailbox and retain the data?

Usually when someone leaves the company there boss want access to their mailbox. Typically I don't disable the user account for 30 days. Export the .pst and more to a storage location.  Another option has been to convert the user mailbox to a shared mailbox so I can free up the license then export to a pst. The Active  directory account does not have to be enabled for  any off these processes. I just want to know how other IT processionals are managing O365 licenses and retaining the mail data.