1.Also, premiss. Logic. a proposition supporting or helping to support a conclusion.
See the difference? Something that’s on-premise is something which is aligned to the original proposition or logic. Something that’s on-premises is located on-site. if you insists, because I know how you kids are with the shortcuts these days, on-prem can be a shortened version of on-premises.
But do not say “on-premise” to mean “on-site.” Correct other people who make this mistake. We will not lose this battle!