Hola, Real lake pls's trick 

This is the key in the regedit to delete everytime you get finished of trial period,
don't delete each val, only press "del" key 
by selecting  " {BF4B9720-A035-11d4-9851-0080AD79471E}  " in the left window of the editor.
you can search it also by pressing F3.

Path to the key :

[HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\CLSID\{BF4B9720-A035-11d4-9851-0080AD79471E}]