I was checking some licensing and was blown away to find:
As sold, Office Home & Student 2013 RT Preview and the final edition are not designed for commercial, nonprofit, or revenue-generating activities. However, organizations who purchase commercial use rights or have a commercial license to Office 2013 suites can use Office Home & Student 2013 RT for commercial, nonprofit, or revenue-generating activities..
The good news is that all you have to do to use it inside your company, is pay again. Microsoft is sooooooo thoughtful. This will not affect large companies that purchase “Open Licenses” as that license now provides commercial RT usage rights. If you are using OEM Office 2013 you are stuck buying an additional license.
See THIS Microsoft blog post for more details.