Why do I receive the error "License Manager Error -4"?

Solution:

This error message indicates that all the keys from your license server have been checked out. You will not be able to access a license for this product until another user has returned the license back to the pool. For information about the current licenses in use you can check with your License Administrator.

Your License Administrator can check the usage of licenses through the license manager server by following the instructions below:

For a Windows License Manager:

1) Launch LMTOOLS, located within the $MATLAB\etc\win{32|64} ($MATLAB\flexlm for releases prior to 2010b). If lmtools.exe is not in that folder, see the related solution "Why are necessary license manager scripts missing from my license manager directory?" below.

2) Click the "Perform Status Enquiry" button on the SERVER STATUS tab to get a full report of the current license usage.

For Unix/Linux/Mac License Manager:

1) Open a terminal Window. For Mac OS X, use the Terminal application located in the Applications/Utilities directory.

2) In the terminal, change directories to the $MATLAB/etc directory. For example:

Linux
______
cd /usr/local/MATLAB_R2010b/etc

Mac OS X
________
cd /Applications/MATLAB_R2010b.app/etc

3) Run the following command to get the usage information

./lmstat -a -c license.dat

--------
Status
--------
Flexible License Manager status on Mon 9/28/2009 15:35

[Detecting lmgrd processes...]
License server status: 27000@license1
    License file(s) on license1: C:\Program Files\MATLAB\R2009b\flexlm\license.dat:

 license1: license server UP (MASTER) v11.6

Vendor daemon status (on license1):

       MLM: UP v11.6
Feature usage info:

Users of MATLAB:  (Total of 2 licenses issued;  Total of 2 licenses in use)

 "MATLAB" v22, vendor: MLM
  nodelocked license, locked to "ID=123456"

    joesmith joe-pc joe-pc (v22) (joe-pc/27000 102), start Mon 9/28 15:37
    janedoe jane-pc jane-pc (v22) (jane-pc/27000 101) start Tues 9/29 08:26