The Volume License brief entitled "Licensing Windows Server 2012 R2 Remote Desktop Services and Microsoft Desktop Applications for Use with RDS" states that, to use desktop apps in an RDS environment, it "requires that the suite/edition, components, language, and version of the license acquired for the desktops from which the desktop application is remotely accessed matches that of the copy of the application being accessed." One of the examples given is that a desktop licensed for Office Standard may not remotely access and use Office Professional Plus. That makes perfect sense to me. However, I'm pretty sure that, in the past, it was permissible for a desktop that was license for Office Professional Plus to remotely access and use Office Standard (assuming both suites are, e.g., Office 2013). When did that change?
And, on a similar note, although a desktop licensed for Office 2010 is not permitted to remotely access and use Office 2013, is it no longer permissible for a desktop licensed for Office 2013 to remotely access and use Office 2010? Because I'm pretty sure that used to be OK as well.