Both licenses cannot be working at the same time in the same machine because each one has limitations and capabilities that the other one does not have.
If you use them in different machines, from the subscription version you will be able to open scenes made with the PRO version with no issues. However, from the PRO versions you will only be able to open scenes made with subscription assets for render purposes, not for creating new content or simulations.
In other words, the actors from a scene made with the subscription will be correctly loaded (and rendered) in a 3dsMax installation that uses a PRO or a Render Node installation, as long as the version number of Anima is the same. However, it is not possible to edit or modify scenes that include subscription assets using Anima PRO.