Using refunded Macbook Pro

I recently had a macbook pro refunded and started using it for school. I've been meaning to download something from the appstore but i had some concerns with using an apple id on the MB. When i ordered the MB i checked out as guest and used an email that is no longer in use. If i were to log in to the macbook with my original apple id could that cause any problems even though it was never used to create the order? Would i be better off creating a new apple id that would be used on the refunded MBP and on my legit purchased apple products? Just wanted to hear from your personal experiences, thanks.

As long as it isn't the original email/apple ID. You should be good. Correct me if I'm wrong?. But as far as I've heard as long as it's a ID with completely different info you're good.