If you find your assets on a piracy site, you can request their removal through a DMCA take-down. Visit http://www.dmca.com/ to flag the site, noting this service isn't free. For Unity-owned assets being pirated, contact Unity Customer Experience directly. Unity cannot remove assets from non-Unity sites. If the pirated material is on the Asset Store, follow the guidance in the linked article on reporting copyright infringement.✨
Cause:
Once a user has your asset files, it is technically possible for them to share these on piracy sites due to the lack of Digital Rights Management (DRM) on Asset Store files.
Resolution:
To remove an asset file from one of these sites, you should make a Digital Millennium Copyright Act (DMCA) take-down request to the administrator of that site.
This is a copyright law that implements two 1996 treaties of the World Intellectual Property Organization (WIPO).
You can flag a website for a DMCA take-down by visiting the site: http://www.dmca.com/.
(Be aware that this is not a free service.)
If however, you have found Unity-owned assets being pirated on a website, please contact Customer Service directly to report this.
Important: Unity Technologies cannot remove assets that have infringed copyright law unless the asset is being distributed on a Unity-owned website (the Asset Store, Forums, Answers, etc).
If the pirated material is on the Asset Store, follow the guidance in the article