how to delete software instalation date from windows registry?

i instaled a software in my windows xp that was for 15 days rdial version, after few days i unstaled that.now i get the registration key for that software, so i instaled that again, but now when i open it, it showes that your trial 15 days are expired. u can not use it anymore. is there any way that i delete its instalation date or intalation information from windows registery. then i’ll instal it again to inter its registration key.

go to control pannel-add or remove…-then select the software and remove it easily.
good luck