Help a newby cracker

Hi, im trying to crack a little scr.
i succeded in making it accept any serial and making it fully functionally but the problem is when i restart it, it is again unregistered.
i found it puts the serial in the registry, but i cant found where is the registry check.
i tried setting breakpoints at every Regqueryvalueexa, but its not showing.
Is there other API or something that checks the registry values when running the prog?
Thanks!