Hi Marta,
Could you check whether you have only a network.lic file, instead of license.lic file. If that is the case, try contacting your license adminstrator to check the license.dat file on the license manager server machine.
If you find the license.lic file and the issue persists, then it might be a result of corrupted fromatting in your license file. Try to ensure that the strings in the file such as #, SERVER, DAEMON or INCREMENT all begin on a left-justified line. Sometimes they might get wrapped on the end of previous line and it might cause them to be omitted.
You can also try re-activating the MATLAB directly which updates the license file, instead of following the above procedure.
Regards,
Pruthvi