You can freely use preview files in your project! Just please make reference to my music at the same time. It would be nice if you tell me using my preview tracks.
All my music is registered and tracked with AdRev. Please contact me directly with your video YouTube link and purchased License Certificate (copy/paste the contents) meaning you will not receive copyright notices on your monetized videos that contain my music. Claims are cleared within 24 to 96 hours.
Thanks for your purchase!