Does Sugar 8.3 API work with On-Premise?

Hello,

Does the 8.3 API work with On-premise customers or just for cloud? I see that it says it's only for cloud. What happens if an on-premise customer uses it? And I see that the newly released 9.0 only mentions on-premise. Does that mean it won't work for cloud?

Is there a version that can be used with both cloud and on-premise?

I only have a trial account, so I am unable to check all cases for now. And if there is something similar to a developer account that I'm unaware of, please point me to it.

Any help would be appreciated.