We have the same problem. We are using Sitefinity Community Edition but we are getting the 'you are running a trial version of Sitefinity' message. In the license file under domains it says 'localhost' I can find no way on Sitefinity.com to change this domain. There is no 'Manage Sitefinity Keys' option that I can find.
We have invested a lot of time in setting up our site in Sitefinity. We love using Sitefinity, and continuously recommend it to our partners, but if this problem persists we will be unable to continue using it. Any help would be greatly appreciated.
Edit: Solved my own problem. Found a direct link to the Telerik License Management panel, where the domain name can be set and the license file downloaded: