Smokinkat Audio provides previews under Creative Commons Attribution Unported 3.0 (CC BY 3.0) which means you are free to:
Share — copy and redistribute the material in any medium or format
Adapt — transform, and build upon the material for any purpose, even commercially.
Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.
You can learn more about CC BY 3.0 here: https://creativecommons.org/licenses/by/3.0/
The Commercial version comes untagged and you don't need to credit the author to use it on your audio-visual projects, it also comes with a stamped PDF file which will be created only for you after the purchase.