The SCADA node is the only node in the system with a Hardkey used for Licensing. Each SCADA node must have its own Hardkey and matching License software control file. In the full-feature version, an unlimited number of clients can connect to a SCADA node (your License may limit this number). The number of Tags is also limited on a given SCADA node by the software control license file.
For more information see:
section 1.5.1 License Tag Limits by Part Number
section 1.5.4 SCADA Node License
section 1.5.5 HARD KEY.