How often i can change my keywords?

My site is indexed yesterday on google and i want to erase all keywords which i was put first time and put new ones.
Can somebody tell me what will happend if i do that? Did google remember my first keywords and if i change with new ones will not give a effect with second ones?
Can my site be penalized by search engines if i change all my first keywords,or google will only erase old links which i was make with first keywords?

all that will happen is that your site will drop off the search for a little while
then it will come back reflecting the change of keywords..