NASM’s Certified Sports Nutrition Coach (NASM-CSNC) is a certification, which means you must renew every 2 years.
On the contrary, the Corrective Exercise Specialization (CES) and Performance Enhancement Specialization (PES) are specializations, not certifications, which means they do not need to be renewed. Once you pass your CES and PES final exams, your NASM-CES and NASM-PES specialization certificates never expire.