Additional SQL Server features and topics not covered by specific categories
With a server + cal license, you buy a sql standard license for the vm you install Sqlserver in. You then buy a CAL for every unique user and devices that accesses the Sqlserver. The number of concurrent users does not matter. If your lab has 20 researches who access the Sqlserver, even if only 2 at a time, you need 20 CALs.
note: if a unique user has 2 pcs, you only need 1 cal for that user. A device cal is required if the device has an unattended program that access the Sqlserver. A batch processor for example, that doesn’t require a user to login to run the batch processor.