nl2, KK, is it okay ?

Well it depends on villain, what info do you have on him? and I don't know if this is right or not but given his stack size and the fact that he lead out on 2 streets I think you can raise the turn to grow the pot so you can shove the river, however check calling is fine as well in my opinion.

the biggest error was preflop my friend ..Never slow play KK PF and call his 3bet ..4bet around 2.2x and get it in ...specially at micros !

if ever you want to slow play a monster hand at higher limit only like nl50 + for deception vs regs that you play them a lot pick AA that is harder to be outdrawn

Post flop was fine ..even if he had AJ

Don't shove on turn, you have the best possible hand and you need to take as much as possible on river, he would probably fold on your turn shove.
Also you should 4bet preflop in this spot, never call a 3-bet with KK and AA. NEVER ♦

Yeah I guess you're right, I'm being a bit results-oriented since my winnings with KK in nl2 are just about 1$ over 11k hands, the times I stood versus Aces balance it. because seriously I mostly find aces calling/shoving my 4bet KK, rarely worse. nits all over nl2 !!! ♦ ♦ ♦