Microsoft SNA Server requires a Server License for the server and Client Access Licenses for all computers that access the SNA Server. You can access SNA Server in many different ways. The most common form of access is through an application, such as Attachmate® Extra or an application developed with Visual Basic, that is accessing SNA services. Although you are not directly connected to SNA Server, the application that you are using is connected and so an SNA Server Client Access License is required.