Hello,
the vocabularies that are not specifically stated to require a license in Athena are open source as a part of OMOP and OHDSI tools. Some of them, such as SNOMED, do have restrictions you pointed out, but as long as you use them for research with OHDSI and do not extract vocabs and redistribute them, you are good to go.
The exact citations of documents can be found in this topic.
Hope that helps:)