With Windows Vista and Windows 7 Microsoft have introduced new security protocols which limit the areas of the registry the programs can write to. However, to maintain backward compatibility the software will actually work but license key will be stored in a user specific area of the registry (HKEY_CURRENT_USER) rather than the global area (HKEY_LOCAL_MACHINE). The consequence is that when you log on as a different user you will have to re-enter the license key and re-activate. Since the machine key is unchanged the activation will work without any problems, however it is inconvenient.
To fix this download the latest Spark-Space software release where this problem is addressed.