(each for circa the price of a computer game)
I don't know whether you want to make this virtual friend-project only for yourselve or to share it whith others. Only if last alternative is true -
are you sure you are allowed for that price to distribute the generated sound files as a part of a commercial or even a non-commercial product ?
When I click on "Site licences" on NextUp.com's site, I find that they speak only of a use related to a special computer you bought the software for. From that I would guess they don't allow distributing .wav-files made with their software. May be the complete license text shipped with the product tells something different...