When do I have to register every time I open the software? I thought this kind of registration is one time off.

That shouldn't be happening Noah and I don't remember anyone raising it as a problem.
You're using Vista or Windows 7 and possibly one of the bottom end versions.. Home or similar???

I'd try:
Start CL in administration mode (don't know the exact English words). Windows then allows CL to write something in it's starting directory ("/Program Files (x86)/CL" or similar) which is normally forbidden.