Answer :
The applied Ethics is related to the daily conduct of a person, and consequently of a professional, including in Informatics. Professional ethics is related to the conduct of the person engaged in the practice of a particular profession. In most professions, including in the area of Informatics, Ethics must be covered in both aspects, in the conduct of the person as a Human Being as well as in the conduct of the Professional Being.
Is it ethical to use proprietary Software and not pay your license to use? No. In this situation the correct and ethical way to act would be to ask for the owner's authorization and make it authorized to work, because using the software without asking for permission would be wrong in all ways.