Affiliate Marketing Secrets

So the thing is this.. i have an small company growing up.. now im requiring some help..
i recived a CV that is very interesting for me, the guy studied the speciality for what my company is about..
the market on this subject is very tight..
so my worries are if i hire him he will learn all what took me 8 years to learn, and in a few months he will just quit and start his new company.. with all my company secrets..
any REAL experiences about that? ,
CEOS? any advise for this entrepreneur?. should i just give him the job or..
thanks!