Have you actually run Access? The reason I ask is because I've now uninstalled Office 2007 from my Win8.1 machine, leaving just Office 2013, and the Access.Application Key disappeared along with it (still got Access.Application.12 and Access.Application.15 Keys though ... loads of .12 Keys.left in fact ). It's only when I opened Access 2013 that the Access.Application Key reappeared along with its CurVer SubKey.

Also, if you don't have the Access.Application Key, is any of this KB article relevant to you?