The primary function of a software license is to regulate the use and distribution of software. It establishes the terms under which the software can be used, including any restrictions or obligations imposed on the user. This can range from open-source licenses, which allow for modification and sharing, to proprietary licenses, which limit use to terms defined by the creator. A software license aims to protect the intellectual property rights of developers while also providing users with clarity on how they can legally interact with the software.