[usrbinbash]

I see no contradiction.

There is a difference between gracefully and responsibly using something that is offered for free, and just bombarding it with requests like no tomorrow.

People can of course do the latter. But then they don't get to complain when at some point, the available offerings present walls of legalese instead of a few simple and clear statements, and the user experience goes from seamless and easy to "Click here to register an API Key"

[ranguna]

It all depends on the nature of the work you are doing.

One thing is to own a service that's used by 10 MAU and you extend the service with a job that calls the OP's service 100 times a second. That's bad, you are using way more than you need.

Another thing is to own a mobile app used by 10M MAU and you embed the OP's service into the app. That's not bad intention, you just added a new service to your app. The problem is that the OP's definition of "unlimited" is not really unlimited.