Normally, the evaluation copy of Office 2010 works only for 30 days, then you have to register the product using a so-called activation key.
However, there is a little trick that makes it possible to extend the trial period by 30 days. The trick can be performed five times, making it possible to test Office 2010 for six months before the suite must be registered.
The trick is to run a small program called “ospprearm.exe“. The program is located in the following folder after installing Office 2010:
“C:Program FilesCommon FilesMicrosoft SharedOfficeSoftwareProtectionPlatform”
A Microsoft spokeswoman has confirmed that the program can be used up to five times to extend the trial period.