LISH is the acronym for Last-in, Still-here and is basically just another name given to First-in, First-out (FIFO) method which is a well known inventory valuation method based on particular cost flow assumption.
Different authors sometime coin new terms, this might be one of them.
As FIFO is the widespread term and is also used in many standards so to my opinion it will be good if we just stick with FIFO.
So, LISH is not a new inventory system in itself and also its not a modification any existing popular inventory valuation method.
Just to add to your general knowledge, just another interesting term is FISH which is the acronym for First-in, Still-here and is just another name for LIFO method.