Of course money is a relation, not an object. Social institutions are not objects, even when they feel like objects in use. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
But the point is that "Money" is not in fact a "thing".
A Value Unit is abstract, and is a necessary part of the Money relationship.
A Value Unit is a "Unit of account" and also a "Medium of Exchange".
As for "standard of deferred contract payment", yes, a monetary system exists to split barter transactions over time.
But a "Store of Value"? Conventional interest-bearing money operates in this way, of course.
But in reality, definitely not. A "Store of Value" is what "Capital" is all about. "Any economic unit can emit money. The serious problem is to get it accepted" Hyman Minsky
