Any "hidden" third party software licensing costs?

Putting the question out there to anyone who may know. Are there any third party software used in the UE4 code on github that the developer would have to pay for upon commercial release? Software that comes to mind: third party audio software, physics, speed tree(?), other?

I asked this exact question today, at GDC.

Epic assured myself (and others there) that what you see is what you get. Even the AAA guys are paying $20 / mo + 5% royalties. No hidden fees.

Granted, if you wanted some specific 1-on-1 service or to have engineers fly out to work with your studio, that would require some sort of special deal.