When trying to license getting message: invalid license number, unknown, and no connections allowed
1) If you have downloaded Spotlight on SQL Server and you are trying to license Spotlight on SQL Server Enterprise you will receive message invalid license number since these are two different products.
2) if your Diagnostic server is not setup or cannot communicate with client, you won't be able to edit or add license key (from Help- About menu). You will receive message: "unknown", "no connections allowed" since the licesing event thou is entered trough clients GUI it is licensing from DS machine (in versions 6.0 and later)
If that doesn't help , re-install the Spotlight's client only.