You enter 3 licenses into the SEPM with 10 seats each but in the license overview he can see only 1 license and 10 seats. The other 2 licenses are shown as associates license for the first one you entered but the number of seats is not going to be raised.

Multiple licenses installed do not increase the total license count.

Click on 'Recover a deleted license' to see the licenses which have been associated with the first one. Select them and click on submit.

The deleted licenses should now be correctly in the SEP  manager.