I am quite sure that you can provide fmod as a seperate download from your site. It may also be possible to include it with your release, but for sure you'll need to keep it in it's original archive form either way you do it.

Freeware and shareware are meant to be distributed around. FMOD has sort of a funny clause where you can include it in your programs if it is freeware, however if it is not freeware(shareware or commercial) then you have to purchase a licence.

So taking this into consideration I'd say, just include it, BUT also include in a very noticeable way the FMOD licence agreement with a disclaimer in your licence or readme, etc...

This should cover your ass 100%.