Comment by gnfargbl

If you are a freelancer then your contract should allow you to do work for others. In which case, your response to this client has to be "Sorry, but my business laptop potentially has data from other clients on it. I can't let you install this monitoring agent without violating my contractual confidentially agreement with those other clients. I always maintain client confidentiality and will do the same for you. If you want to ship me a dedicated laptop for your engagement, I would be happy to install whatever you want on it."