Webstore, How to apply new offline license file for MATLAB on Mac OS X
You will need to re-activate MATLAB with the new file. First, try, Help->Licensing->Update Current License from within the MATLAB application. You will find the standard Help menu in the OS X menu bar, and then there is the MATLAB Help menu in MATLAB's toolstrip. The licensing submenu is located in the MATLAB Help menu, marked in the toolstrip by a white circle with a black question mark inside.
Another method to do this in OS X is to go to the Applications folder, ctrl-click on MATLAB_R*.app, select "Show Package Contents," then run the "Activate.app" application.