Cheat Engine

[Fulikia]

i'm trying to edit/inject codes so that the game activation process will always approve the activation code regardless of what i had typed in.
the targeted game is called "Legend of Heroes: Zero no kiseki".

it is a Jap game in PSP that sells its license to China and ported the Chinese version of the game to PC, and allow people to download the game online but must pay to get the activation key in order to fully activate the game.
the activation key is asked to be filled when the game starts, not while installation.

here's a picture of the activation screen.


the first textbox is called 'Serial key'.
the 2nd textbox is called 'activation key'.
the 3rd textbox is called 'machine code'. it is automatically generated.
the two darkblue button below them, the left is 'activate', the right is 'back'.

please suggest me a solution.

additional info:
i originally planned to look for the opcode associated with the 'activate' button and place codes that do nothing all the way until the key verification process ended. so that the whole verification process will always do nothing and always approve whatever i input for the keys.

if i am to follow what i had planned, then i had a few problems.
1st, i don't know what kind of INT represents (activate) button click
2nd, how to determine where the verification process ended.

i had some programming knowledge myself, but is completely new to asm. if there're some useful tutorial, and possibly not too long, then i will be glad to read and learn from there instead of bothering you guys for explaining stuff to me.

any help is appreciated, and sorry for the long post.