What is the ruling on divorce oaths that the husband does not remember?

The majority of scholars hold that a conditional divorce (talaq (definition) mu'allaq) takes effect when the condition is met, regardless of whether the husband intended divorce or merely a threat. So, if you conditioned your wife's divorce on her leaving without your permission, and she did leave, the divorce takes effect. As for matters on which you conditioned divorce and then forgot them, the divorce does not occur due to doubt, because certainty is not removed by doubt.