That which is not created is eternal. What is eternal is that way either from being sustained eternally by an ontologically prior being or through its own essence. If its not the former, then the being is noncontingent. To be noncontingent is to be complete in being (as your nature explains your existence perfectly, meaning there is no room for external influences. That be so, it cannot have potentiality in any regard. But that requires complete actuality. Thus, the noncontingent being must be pure actuality). But the mind is most certainly not complete in being because we are lacking completness in knowledge, power, and comprehension. Thus, the mind is not noncontingent. There is no avoiding this conclusion unless you say that an externality makes you eternal, but that means you are not noncontingent, nor metaphysically simple, nor immutable, nor an uncaused cause. All the elements you need for your idea of free will.