Since MATLAB is already installed from one license, all you will need to do is deactivate your current license and then activate your new license file, this essentially swaps your license files. Please refer to the instructions below:
If your old license does not have the same list of toolboxes that your new license does, you will need to install the new toolboxes into your existing MATLAB installation. For instructions on this, please see the following article:
How do I install additional toolboxes into an existing installation of MATLAB?