can someone tell me the name to this ?
things i can remember : the guy seems to remember her but she doesn't realize it until later on (because they were in an incident when they were really young) and he also likes her.
it's ongoing but i can't seem to remember the name
please help.

are you talking about Mission: Yozakura Family manga?

Be kind or get banned

unfortunately it isn't that one 🙁
the male assassin/spy/hitman also betrayed his former colleagues and one of them came back to get revenge and ended up kidnapping the female to grab his attention. somewhere along those lines.

Is it "Koroshi Ai" ?

At the beginning i thought it might be Angel Heart but I'm probably wrong because not every thing fits and its not the main point of the story

IT IS !
Thanks a lot
I lost most of the brain cells I had trying to remember the name