Final answer:
Using unlicensed proprietary software is called piracy, which is illegal and infringes on the economic rights protected by copyrights and patents.
Step-by-step explanation:
Using unlicensed proprietary software is referred to as piracy. Piracy involves unauthorized use, copying, or distribution of software that is protected by intellectual property laws. Copyrights and patents are forms of intellectual property that provide creators with exclusive rights to their work. When software is pirated, it undermines the economic rights of the creators and is illegal. An example of where copyright law has been enforced is the Supreme Court case MGM Studios v. Grokster (2005), where the court held that companies distributing file-sharing software that enabled copyright infringement could themselves be liable.