What is the last book in alchemist series by Micheal Scott?

There isn't actually a series called "The Alchemist" by Michael Scott.

* The Alchemist is a novel by Paulo Coelho, not Michael Scott.

* Michael Scott is known for the "Percy Jackson & the Olympians" series and the "Heroes of Olympus" series, among others.

Perhaps you're thinking of a different series by Michael Scott? Could you clarify what you're looking for?