A license permits you to use software, content, and services in accordance with certain terms and conditions set out in an End-User License Agreement (EULA). A EULA is a legally binding document. Without entering into a EULA, you can't legally use the software, content, or service.
When you purchase software you are buying the right, or getting a license, to use the software in accordance with the EULA.
The EULA explains exactly how you can use the software you purchase and identifies specific restrictions on your use of the software. If you break the terms of the EULA, you are subject to enforcement action and penalties.