You can include the ACF PRO plugin within a premium theme/plugin as long as it is made clear in the copyright / information that the ACF PRO files are not to be used or distributed outside of the premium theme/plugin.
You can not include the ACF PRO plugin within a free theme/plugin.
You can not include a ACF PRO license key within the theme/plugin/materials.
You can include the (free) ACF plugin within a free or premium theme/plugin.