A concurrent network license allows users to run MATLAB concurrently (one user at a time per license key) on any computer. This license can consist of 1 or more keys of MATLAB and any number of additional toolboxes or other products.
You can check the network.lic file int he MATLAB installation directory By default, the license file location is $MATLAB\licenses for all platforms. The license file name will be network.lic
On Mac's this file is located in /Applications/MATLAB_R2011b.app/licenses/network.lic
On Linux systems it is usually located at /usr/local/matlabR2011b/licenses/network.lic (conditional to the install location being /usr/local)
Open the network.lic file
SERVER lmgr@*.* Port#
USE_SERVER
This shows a concurrent network license and the license is checked out from the flex lm license manager located on the server "lmgr@*.*" at port "Port#"
Or as Sam suggested unplug the network cable and initialize MATLAB.. If it starts up you have a designated computer license.