Vista - Where to save trial version information?

Since I'm not allowed for system32 and program files to write anymore
with a simple user account - where would you put trial start dates?

I mean: HKCU is propably _not_ a safe position, since you simply
create a dummy user account and overwrite it every week or so...

--
-Gernot
int main(int argc, char** argv) {printf
("%silto%c%cf%cgl%ssic%ccom%c", "ma", 58, 'g', 64, "ba", 46, 10);}