Not sure what you mean by "primary" money, but I can't think of a definition that would make that statement ("is strictly conserved") true.

All money is in the books of the central bank, and it all has counterpart assets to it, and is all based on contracts with a maturity of less than a year. So if no-one renews there is no money, regardless of definition, in circulation after that time.

Edit. Coin would be the only exception, but that's a negligibly small item in the balance.