What is the ruling on copying computer programs that I have not purchased?

It is not permissible to copy programs that their owners prohibit copying, except with their permission, because the Prophet Muhammad, peace and blessings be upon him, said: "Muslims are bound by their conditions," and "The property of a Muslim is not lawful except with his willing consent," and "Whoever precedes others to a permissible thing has a greater right to it." This applies to both Muslims and non-belligerent disbelievers. Sheikh Ibn 'Uthaymeen clarified that custom is to be followed, and that if the program owner explicitly prohibits private and public copying, then it is absolutely impermissible.