Does janusSEAL for OWA need a license to operate?

Yes.
 
Version 2.1 of janusSEAL for OWA does require a license to successfully operate. Your organisation would have been supplied with license details when you purchased janusSEAL for OWA, or if evaluating the product janusNET would have sent you an evaluation license. These details must be supplied to janusSEAL for OWA via Group Policy administration.
 
Version 2.0 did not require a license to operate so if upgrading from that version be sure to specify the license details in Group Policy as part of the upgrade.