If you are a paying subscriber from 2001, you have a perpetual right to use the media you received. If you are downloading it from an archive today, you fall into a gray area. Most vintage computing communities operate on an "honor system": download only if you own a licensed copy of a relevant Microsoft development tool from that era.

The interface relied on the (DExplore). This was a standalone application designed to handle the massive database of help files.

It depends on your jurisdiction and intent.