Open word, click on help, then select activate product.

;->

If you have a product key for enterprise, it will not work for lower grades of Office, such as professional or Student or Academic or Business editions.

The only thing that key will activate is a copy of the enterprise edition.

You can activate the product by going into any one of the software modules, like Excel or Word, click on the office button in the upper left hand corner, go down to Word Options (if in Word) button, click on it, Resources and then click on the Activate Microsoft Office button.
You can only register it if you already have the key entered and this is the FIRST THING that the office installer asks you for.

You CANNOT activate a 60 day trial version beyond 60 days…you cannot download another copy of the 60 day trial and make it work and you cannot just upgrade directly from a full version when a trial version is on the computer. You must uninstall the trial version in order to install the full version, but you need a CD for this.

Are you sure it’s not already activated? I thought I had to enter the key during installation. Anyway, try opening one of the apps like Word, then click on the “orb” in the top-left of the menu, then Word Options -> Resources -> Activate.

*Edit: thumbs up to Jim who knows his stuff.

Recover your product key for Microsoft Windows and Office.

even tough you do as suggested by the guys, it also depends the version of the product key and the version of office enterprse you’re activating.if the version does not match each another it won’t activate.
normally office enterprise comes in Medialess License Kit (MLK License)-for this you’ll need to download the office enterprise from and activate it using the Product key you have, BUT also do remember uninstall any other free/trial version of office you have installed on the machine as they’ll conflict with each another.
Been there, done that.
Hope all goes well.
Good Luck mate !!