After renewing the MATLAB license, you'll need to update the license file on your computer. In order to do this before the current license expires, do the following:
1. From within the MATLAB application, select the Help menu then Licensing > Update Current Licenses…
2. Select the license and click Update.
3. Click Yes to confirm.
4. If prompted to enter your computer password, do so to allow MATLAB to copy the license file.
5. Click Close to close the License Update window.
After restarting MATLAB, you should be set up to use the updated license file.