The PSM build option works with both the free and Pro versions of the Unity game engine.
The new release features in-app purchase APIs and also allows developers to distribute their titles to PlayStation TV.
Unity for PS Mobile differs from the existing Vita build option however. PSM support is designed to provide free access for development on a standard retail Vita, while the existing Vita build option provides full native access to the handheld and full access to PSN.
Visit the official website for more information.