The communicator for web requires in 9.1 as well an additional license, I think from release 10 it should be included in the power user license, so if you upgrade you save buying these licenses as they are part of the power user within 10.
More Information via,
https://www.avaya.com/en/documents/a...b---uc7752.pdf
I think these license refers to WebRTC within the knowledge base article about licenses.
Release 10 still needs licnenses for MAC Softphone.