Complex sentence: Holding a "Licenciatura" degree does not, however, ensure the right to practice in all fields; by their nature, disciplines such a Nursing, Medicine and Law may take longer to complete and require passing a national exam.
Split into simpler sentences: Holding a "Licenciatura" degree does not, however, ensure the right to practice in all fields. Disciplines such a Nursing, Medicine and Law require passing a national exam.