I delivered a drawing to a client and he refused to accept it so I refunded him. Can the client still print the drawing even if a mutual cancellation was made by me? The cancellation was made after the job was delivered.
Not legally, no. But it’s very difficult to catch. If you do see that the person is using your material somewhere on the internet, notify the website’s administrator and let them know that the person is illegally using copyrighted material.