A customer of mine experienced a problem when some of his IT staff installed a 90-day evaluation version of Windows NT Server 4.0 on a pilot project. The problem was that the project turned out to be a production pilot running live data, and the evaluation software was going to expire. To prevent the customer from losing data, I had to determine which servers were running evaluation copies of NT Server. Then, I had to convert the installations to retail versions of the software without reinstalling everything.
To determine the software version each server was running, I used SavillTech's Win Info, a freeware utility that told me not only the servers' Installation Type (i.e., Evaluation or Licensed) but also the Installation Date, so I knew the amount of time before the evaluation versions expired.
My next task was to convert the evaluation copy of NT Server to a licensed copy of the OS. For this task, I followed the instructions in the Microsoft article "Evaluation Period Expires of Non-Evaluation Copy of Windows NT" (http://support.microsoft.com/support/kb/articles/q173/5/07.asp).