Licensing models can sometimes make database modeling seem trivial. Per processor or per seat? Single core, dual-core, multi-core processors? Multiple instances on one server? Virtualizing servers on a single server? It can get very confusing, very quickly.
I’m regularly asked by a former students, clients, and people in the Forums about licensing for a SQL Server Reporting Services instances. A typical question is: How many SQL Server licenses are required when the Report Server is installed on one server and the back end database is installed on a separate remote server?
Here are a couple of links that help describe the SQL Server licensing models.
And by the way, the answer to the sample question? Each server where a Business Intelligence component is installed requires a valid SQL Server license. So, a remote database deployment scenario where the Report Server is installed on one server and the ReportServer database is installed on a separate server requires two licenses of SQL Server.