A Concurrent Network License (available for Version 9 and earlier) provides a specific number of Named User Activations, which is the maximum number of computers on which a named user can activate the application (i.e., make it available for operation). More than one activation is allowed for each named user (e.g., to install the application on both a work computer and a portable computer), but each activation is counted toward the maximum available under the license.
Out of that pool of Named User Activations, only a certain number can use the software at the same time. The number of Concurrent Access Licenses (CALs) determines how many computers can access the software simultaneously.
For example, for a Concurrent Network License with 30 Named User Activations and 10 CALs, the application can be installed and activated on up to 30 computers (e.g., by 30 named users each activating the application on only one computer, by 15 named users each activating the application on two computers, etc.), and only 10 of those computers will be able to access the application at the same time. If a user attempts to access the application from an 11th computer, the user must wait until one of the other 10 users ends their session and releases the CAL.
From the user's perspective, there are a few things to keep in mind about Concurrent Network Licenses: