Web Front End (WFE) servers are the servers in your deployment that run the Web Application service. You need to purchase one license for each WFE Server. A unique license key is provided for each WFE Server in your deployment. To determine the number of WFE servers, please log into your SharePoint Central Administration website or contact your SharePoint administrator.
The Perpetual License includes 1 Year of Support and Upgrades in the first year. To continue to receive support and upgrade you will need to purchase a subscription renewal. With a Perpetual License you can continue to use the software after the Subscription period ends.