So I did some digging, and apparently neither Wwise nor FMOD provide 3D spatial audio, unless this plugin is purchased: http://twobigears.com/3dception.php
So while Wwise has free license limited to 200 sounds, and FMOD has free license for unlimited number of sounds (but only 1 free project per year), we’d still have to fork over undisclosed amount for 3D spatialization plugin 
Please correct me if I am wrong.