Like any horoscope, it can be interpreted a couple of ways. On the surface, the statement says that 'I will remember how you treat me, so be careful'. The real question is how to interpret "be careful." It can be taken as a threat or a plea.
As a threat, it implies the possibility of revenge. "Be careful how you treat me or I'll make your words come back to haunt you."
As a plea, it suggests that "Be careful how you treat me because if you hurt my feelings, it will hurt for a long time."
Horoscopes are often ambiguous so they will apply to the widest range of people and situations. Take your pick as to how this applies to you.