We asked some folks at Oracle about this, and my understanding is that this fee is imposed by the vendor providing the Opus implementation for their DSPs. Oracl

We asked some folks at Oracle about this, and my understanding is that this fee is imposed by the vendor providing the Opus implementation for their DSPs. Oracle is just passing on this cost. A specific implementation may, of course, include technology which has additional licensing or fee structures on top of the basic royalty-free license used with the reference implementation.