to have said that
Tom no recuerda haber dicho eso.
Tom doesn't remember saying that.
He couldn't have said that.
He/She can't have said that.
I regret having said that.
No recuerdo haber dicho eso, creo que me estás confundiendo con otra persona.
I don't remember saying that, I think you're confusing me with someone else.
Tom no debería haber dicho eso.
Tom shouldn't have said that.