Here I would like to help for common question that every DBA has when it comes to SQL Server Licensing.
Refer http://www.microsoft.com/en-in/server-cloud/products/sql-server/buy.aspx for different licenses available.
1. What is Per User license?
Ans) Its not the number SQL users that could be created. Its the number of people who use the SQL Server on a server.
2. Per core license:
Ans) Its the number of physical cores placed in sockets on a physical machine. Its not the number of cores you see in task manager.