Use the Enter Product Key wizard to enter a product key for a server running Microsoft Exchange Server 2007 that does not already have a product key configured.
you can use the Enter Product Key wizard in the Exchange Management Console or the
Set-ExchangeServer cmdlet in the Exchange Management Shell.For more information about the
Set-ExchangeServer cmdlet, see
Set-ExchangeServer (RTM).
After you complete the Enter Product Key wizard or run the Set-ExchangeServer cmdlet, you must restart the Microsoft Exchange Information Store service so that the change is applied. Depending on the product key that you enter, Exchange
will determine if the server is running Exchange Server 2007 Standard Edition or Exchange Server 2007 Enterprise Edition and will update any necessary settings.