Files with plu file extension are used by Portable License Utility from Autodesk.
PLU file extension - Portable License Utility data
What is plu file? How to open plu files?
File type specification:
The plu file extension is associated with the Portable License Utility (PLU), a tool developed by Autodesk and used to check out a license from one standalone, software-locked Autodesk product (2009 or earlier) and use that license on another computer that had the same product (and installation type) installed.
The plu file stores some kind of data used by Autodesk PLU software.
This plu file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.