once noone replies, i'll share my understanding, but i didn't have any experience with that i think because they can (demand money from anyone due to intellectual property).

i'm not sure if anyone have challenged it. or i may be wrong and basically they can enforce their demands based on usage of their brand only. or noone really has needed that, because everyone is happy to collaborate with the arm company in some other areas besides licensing, so this very fee is nothing for them.

I am not an expert, but here is the extend of my understanding. What your paying for is not necessarily the instruction set, your paying for other things. So, lets take ARM as an example. When you pay ARM, you are buying a license, which I believe comes with some pre-made stuff you can use for your own ARM chips you design and essentially support. If you and I decide to make a new fancy ARM chip that we will put in thermostats, we pay ARM and they will give us a lot of building blocks as apart of that license. We can choose to not use them, but it is almost silly not to. As another example, Apple and the M1 and A-series chips. Apple did not design every aspect of those processors. They almost certainly used building blocks that ARM gave them and then essentially added on their own little twist. I don't want to diminish Apple's work, regardless, what Apple has shown that ARM chips are capable of with the resources it uses is still amazing. With the license, you also get engineering support from ARM or ARM will help you design and implement some of your features.

Because instruction set designers don't seem to have the same urge to work for free as software developers.