We consider the Noetherian properties of the ring of differential
operators of an affine semigroup algebra. First we show that
it is always right Noetherian. Next we give a condition, based
on the data of the difference between the semigroup and its
scored closure, for the ring of differential operators being
anti-isomorphic to another ring of differential operators.
Using this, we prove that the ring of differential operators
is left Noetherian if the condition is satisfied. Moreover
we give some other conditions for the ring of differential
operators being left Noetherian. Finally we conjecture necessary
and sufficient conditions for the ring of differential operators
being left Noetherian.