Is it permissible to use an unlicensed copy of Windows or any other program, knowing that there is an agreement from the company prohibiting this, especially if explicit consent to this agreement was not given during installation, and is mere knowledge of the condition sufficient to establish sinfulness?

The determining factor is what is agreed upon between the software buyer and the company. Thus, whoever purchases a copy is permitted to use it, provided they adhere to the company's terms, whether attached or displayed during software installation. It is not permissible to use pirated software, as that infringes upon the rights of its owners. This is because it constitutes an assault on intellectual property rights, which the Islamic Fiqh Academy considers to be legally protected. A company's breach of its commitments does not justify infringing upon its rights or releasing oneself from the terms, based on the Almighty's saying: (O you who have believed, fulfill [all] contracts), and the Prophet's saying, peace be upon him: "Muslims are bound by their conditions."