A user can have multiple instances of SlickEdit running on the same host machine. Each instance is given a new Checkout ID, but does not consume an additional license as long the same user is running from same host machine.
License admin can remove checkouts from selicutil using the remove command and ID numbers you want to remove:
selicutil -s port@host remove 0 1 2 [ID#]...
or you can use the reread command:
selicutil -s port@host reread
Reread refreshes all licenses and evicts all checkouts. If an active user is removed from the server, SlickEdit will prompt the user that they need re-acquire a license.
There have been cases where older versions of the license server will sometimes retain checkouts after a unexpected shutdown on the client side. You can contact SlickEdit customer support and let them know which version of the license server you are running and see if there is an updated build available.