Hiring a Freelance for SEO Tech Audit Agent

I'm considering hiring freelancers to develop agents to improve our SEO work. I've outlined all the required steps and logic for the tool, and the freelance developer suggested creating it using n8n. One crucial concern is ensuring that the tool I receive isn't duplicated or used elsewhere by them. Besides a non-disclosure agreement, what measures can I take to safeguard my interests in this largely unregulated market?