Office 2010 Volume License edition has two different ways to activate the license.  You can use Multiple Activation Key (MAK) or Key Management Services (KMS).   MAK is like you are familiar with on the previous versions of Office and Windows.  You enter a key and register with Microsoft.  It is a onetime activation for the product.  KMS is a newer way to activate the product and is what Office 2010 defaults to for installs.  If the install is set to KMS then when you get the warning that Office needs to be activated in the next X number of days you will not seen any place on the warning screen to activate with Microsoft.  To switch over to the traditional MAK setup you will need to click on the file tab at the top left of the screen and then help.   On the help page select Change Product Key and enter your MAK license key from Microsoft Volume Licensing.  When the license key is verified as valid, make sure the check box on the bottom left of the page asking to also activate the installation with Microsoft is also checked (default), and click on next.

Office will go on to the Install Now / Customize page.  If you already have office like you want, just click on the install now option.  It will then “install” office how you currently have it setup, but changing the license key over from the default KMS to the MAK settings.

If you are a large business and are looking to use the KMS here are some sites to review about it’s setup.

Here is where you can download the KMS files and basic dirrections on setup: (please not OS restrictions)

http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=97b7b710-6831-4ce5-9ff5-fdc21fe8d965

Here are the TechNet notes on deploying, configuring and a quick start guide to KMS for office 2010:

http://technet.microsoft.com/en-us/library/ee624348.aspx