Even though Non-Disclosure Agreement could have a perpetual time limit and should be theoretically protective to the commercial secrets between the two parties or within the company or institute. However, this is not powerful as a patent since it is not protected by the official government and thus, cannot protect your secret, for example, a crucial product material choice and design, from being plagiarized by other companies. On the other hand, NDA could be more useful than a patent for some family-run companies who greatly rely on their family recipe to maintain their product quality at a leading position among their competitors.