A software license is a document that provides legally binding guidelines for the use and distribution of software. Software licenses typically provide end users with the right to one or more copies of the software without violating copyrights.An open source license outlines the responsibilities taken on by those who use your software.They allow you to define various software license models for a specific customer or geographic location. Perpetual Licensing is the most traditional software licensing model. In this model, the customer purchases software once and keeps it forever. Customers typically pay upfront for the license and sometimes pay a yearly maintenance fee. One advantage of this license is that customers know the exact amount they need to pay, without being surprised by pricing changes in a subscription model. After purchasing a perpetual license, customers often host the software on their servers. Today, many companies are moving away from traditional perpetual licenses to more flexible subscription models (for example Microsoft Office Suite).