Does an NDA actually stop a buyer from using my ideas even if they never buy?

Only if it's drafted to, and this is a distinction many sellers miss. An NDA focused solely on non-disclosure stops a buyer from telling others what they learned, but doesn't necessarily stop them from using the ideas or insights themselves if they walk away from the deal — using information quietly is different from disclosing it, and a narrowly worded agreement may only address the second. A separate, explicit non-use clause is what's needed to restrict the buyer's own use of what they learned, regardless of whether they tell anyone else.

Even strong non-use language has real boundaries: it generally can't reach general industry knowledge the buyer already had, ideas that are genuinely independent of what you shared, or information that later becomes public through no fault of theirs. If protecting specific ideas or approaches matters to you beyond ordinary financial confidentiality, say so explicitly when the agreement is drafted rather than relying on standard boilerplate to cover it. A Treadstone business lawyer can make sure the non-use language actually reaches what you're trying to protect before you share anything sensitive.