You can use 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip.
If you are developing this feature within an application, follow this general logic: : Identify if a file ends in .001 . li14f.7z.001
: If only the .001 file exists, the archive is incomplete and cannot be opened. You can use 7-Zip on any computer, including