Add a License Key to Exchange Server 2007

From the Shell (EMS), you can enter the product key using the Set-ExchangeServer cmdlet:
Set-ExchangeServer SERVERNAME -ProductKey aaaaa-aaaaa-aaaaa-aaaaa-aaaaa
To get a list of all Exchange 2007/Exchange 2010 servers and their product keys and trial status, including number of days left:

Get-ExchangeServer | Select name,ProductID,*trial*

(Note: I typically format this as a list rather than a default table, particularly for a smaller number of objects. The table tends to chop off bits of a field when you have too many fields displayed:

Get-ExchangeServer | Select name,ProductID,*trial* | fl

The output looks something like this:

Name: E12EDGE
ProductID:
IsExchange2007TrialEdition: True
IsExpiredExchange2007TrialEdition: False
RemainingTrialPeriod: 29.19.12.55.8950288

Yes, the timing displayed is very precise, down to the seconds and milliseconds :) – but you can probably tell it’s 29 days.