- Processor License: This is the simplest option. It is also the most expensive. You pay a flat rate for each CPU running SQL Server, and that's it.
- Server plus device CALs: CAL stands for Client Access License. Under this scheme, you pay one price for the computer running SQL Server (no matter how many CPUs it has) and a separate price for each device that accesses the data.
- Server plus user CALs: Almost the same, but in this case you pay for the server plus you purchase a CAL for each user that accesses the data.