Microsoft Office licensing?

I have seen a conversation taking place in one of the online forums about how Microsoft Office is licensed and how secondary use rights fits in. To that end, I thought I would post this information here to address the question and for others to use in their understanding of this. Here are the basics:

Microsoft Office is licensed on a per device bases. What this means is you need a Microsoft Office license for every device that is going to run Office.
Microsoft Office is not licensed on a concurrent basis, which means it is not based on the number of devices running Office at one given time, it is based on the total number of devices that run Office. For instance, if you have 10 PCs in your company and want to run Office on all of them; however, only 5 PCs will use Office at any one given time, you will need 10 Microsoft Office licenses since you have 10 total devices that will run Office, not just 5.
If you plan to run Microsoft Office from a network device such as a file server or through something like Citrix or Terminal Services, make sure your Office license has Network Storage and Use Rights. As discussed in many prior posts, there are differences in licensing rights between OEM, Retail Box, and Volume Licenses for Microsoft products. Network Storage and Use is one of those rights, as is Downgrade Rights, and Transfer Rights. Volume licensing does provide these rights; whereas, OEM Office licenses do not. You can read more on this at: Answer to a question on how Microsoft Office is licensed in a Terminal Services environment and why OEM Office doesn’t cover it, in plain English as well as looking at:

Remember, you can add Software Assurance to your OEM Microsoft Office licenses within 90 days of purchase to get Volume Licensing rights for them. Take a look at these items for more on that: