Just licensing when expressed as part of the ontology.
Note: it enables you explore and assess the inference power. Note, this is limited to OWL.
Virtuoso is an innovative enterprise grade multi-model (RDF and SQL) relational data server for enterprises & individuals alike. It delivers a platform agnostic solution for secure data management, access, and integration. The unique hybrid architecture of Virtuoso enables it to offer traditionally distinct server functionality within a single product offering that covers the following areas: • SQL compliant Relational (Tables) Data Management • SPARQL compliant RDF Relational (Property Graph) Data Management • Content Management • Linked Data Deployment (exemplified via DBpedia and the LOD Cloud Cache).
RDFS and OWL. SQL Relational Schema and RDFs and/or OWL.