What is the plural possessive form of premises?

The noun 'premises' is a singular noun as a Word for a building and the area of land that it is on.

There are two accepted forms for possessive singular nouns ending in s:

Add an apostrophe (') after the existing s at the end of the Word: premises'

Add an apostrophe s ('s) after the existing s at the end of the Word: premises's

The noun 'premises' is the plural form of the noun 'premise', a Word for a statement or idea that is accepted as being true and that is used as the basis of an argument.

The possessive form of the plural noun premises is premises'.