shelfware
Shelfware is slang for software that a company buys because of a perceived need or demand but never uses; hence, it sits on the shelf.
A company might end up with shelfware if they fail to consider whether the software is backwards compatible and capable of working with legacy applications. If a company purchases software they find they cannot use, some vendors will accept returns or exchanges.
See also: COTS, MOTS, GOTS and NOTS, vaporware, scareware