The two types of royalties most commonly encountered are:...

The two types of royalties most commonly encountered are: royalties for the use of copyrights, trademarks, and patents; royalties from the extraction of oil, gas, or minerals from your property. However, other types of royalties are possible, such as those paid for the use of a name, the sale of products using certain proprietary processes, etc.

This is from a search regarding royalty payments.
As you can see the bit in red is a possible contender for CDY
Think in their case it may have more to do with the supply of MK rather than the actual patent itself