Note that the license file you have obtained from your account is a Trial license for the Sitefinity 4.0 RC. The RC is available only as a trial because it hasn't been officially released yet. There is no problem to go ahead and use the same trial license file on your staging server. The Sitefinity website will work in trial mode and display a random "trial message," if it is accessed outside of localhost. Neverteless, the website will be fully functional until the trial RC license expires on January 31, 2011.
If you intend to go on a production server with the RC, please review the forum post available here
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