The Enterprise version of Microsoft Dynamics CRM offers you besides the common known Multi-tenancy, the option to divide 6 server roles over separate (virtual) servers. The easy way is to follow the option to split Microsoft CRM Server in application en platform server.
In general this is advised if you use more organizations or use a lot of workflows and/or batch imports etc. More details you can find at post of crm team.
The issue I was confronted with: “how separating server roles influence the licensing?” I simply thought I buy the Enterprise edition, so this would be covered by this license. After asking around at Microsoft, some Large Account Resellers, the answer was not really surprising. You need a license for every server, so if you split Microsoft Dynamics CRM Server into several server roles, you will need server license for each (virtual) server.
I think a good thing to keep in mind, if you considering this option.