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Log in as the system administrator and install it. The local admin privileges in your case may not have enough permission to update the required registry keys.
In few cases, Windows update KB2918614 causes Windows installer to malfunction.
Microsoft forum post
Uninstalling the Windows update pack (and rebooting) should resolve the issue and allow RAM Structural System to be installed. We expect further updates to Windows that will also resolve the problem.
Structural Product TechNotes And FAQs
Structural Products Licensing FAQ
Non-Interactive Installation of Structural Products