In truth, there’s no way to prove that this is a coin of Nektanebo II. He did mint coins with his own name (one of the very few coins with Egyptian hieroglyphics), but those are beyond my means. This coin, generally believed to have been minted before the Archaemenid period, falls in the time period when he ruled.
For those who are confused, yes, this looks almost exactly like the famous tets minted by Athens. That was a standard currency at the time, so it made sense for others to copy it. Throughout the region, Athenian owls became the standard. Besides using those minted by Athens itself, other countries minted their own.
Nektanebo II was famous for not being the father of Alexander the Great. In the Alexander Romance, Nektanebo disguises himself and seduces Olympias. Nothing of the sort occurred, but millions of poorly educated people during the medieval times believed this.