What are the license terms of Microsoft products that are no longer supported?

Many Microsoft products that have reached end-of-life continue to be sold as part of an MSDN subscription. For instance, Windows 3.1 (released in 1992), MS-DOS (1981), Office 95 (1995), and Visual Basic 2.0 (1992) can all still be purchased in this fashion.

Unlike most abandonware, where the company that sells the products are long gone, Microsoft is of course still around to enforce their copyrights. Therefore, use of their software is still governed under the End User License Agreement those products were shipped with.

While I doubt they'll be adding Windows Genuine Advantage activation features to Windows 3.1, if you're caught using unlicensed Microsoft software in a business setting, you'll certainly still face stiff penalties no matter how old the software is.

If you want to legally acquire such software, check places like eBay, other sites that sell used software, or your local flea market or thrift store. You can also purchase an MSDN subscription if the software you want is included with that (Excel XLSX).

See this post on Abandonware from Wikipedia:

Abandonware are discontinued products for which no product support is available, or whose copyright ownership may be unclear for various reasons. Abandonware may be computer software or physical devices which are usually computerised in some fashion, such as personal computer games, productivity applications, utility software, or mobile phones.

Consider giving the article a deeper read...Also consider checking out Microsoft's own website (thanks @Linker3000).

This in no way, shape, or form states Microsoft's license terms on their old products - just a general read for your information.