how to upgrade from free version to pro without losing the settings. I’ve already bought the pro version.

Hi.
I’ve been using the free version for a while. I’ve configured all my transactionals emails. But i need more options for different product categories so i’ve already bought the pro version. The problem is that i don’t find the way to upgrade my version. The only instructions i’ve seen are about installing the pro version not about upgrading.
Is it possible to have your advice about this?
Thanks for your helpful attendance.