The reason why the registration problem exists even after keying in several times, is that the application cannot save the authenticated license information to the Folder HelpDesk public folder. As the license info cannot persists, you are asked again and again to key in.
The solution to this issue is to perform the registration by a helpdesk user who has owner rights over that public folder. If you are sure you had it when you keyed in, then the permission mechanism had gone awry with regards to that public folder. In this case, you need to reset your permission to none, and then after 5-10 mins, reassign owner?s rights. Perform the key-in and you should be good to go.