Nevada has an adult-use (recreational) program that requires customers to be at least 21 years of age. Medical patients with a valid medical card or certificate are required to be at least 18 years of age. Since Nevada offers reciprocity, out-of-state medical patients are required to be at least 18 years of age also.
See also:
What are the purchase limits in Nevada?
How do I obtain a Nevada medical marijuana card?
What information is required to shop in Nevada?