Watch out, Receiver. This is your last shot - or someone else's. Perhaps this Bearer has been hurt before (by you, or by others they consider of a similar bent) and this is a warning - or maybe someone is begging you for a single opportunity to prove themselves.
Bearers issuing an ultimatum are possessed of generally positive sentiments regarding the Receiver, but all too aware of potential difficulties, wishing both to caution the Receiver and perhaps to gently establish the upper hand from the start. It is considered courteous of the Bearer to ensure the Receiver knows the precise nature of any situation prompting such a gift, as well as what constitutes a mistake. Failure to do so, except in the all-too-frequent and frustrating circumstances where such knowledge eludes the Receiver, is the height of bad manners. Likewise, it is exceedingly inappropriate for those pleading for licence to do so unless they are reasonably certain of their ability to fulfil such a promise.
Should the Receiver wish to convey acceptance and understanding, I understand or Fair enough allow them to do so; And my axe! promises additional support and protection. If the Receiver feels responsible for the Bearer’s pain, Forgive me accepts this and offers a profound apology, Never again promises never to repeat their actions, I'll make it up to you promises reparation, and Trust me begs for renewed trust. On the other hand WTF? or Get over it sharply repudiate the whole idea - albeit in sufficiently stark terms that a Bearer may well wish to retract any accord, conditional or otherwise. Tread softly or It's complicated suggest both parties should conduct themselves with care, whereas #82 recommends the Bearer tone down their demands, and So it has come to this wryly or humorously acknowledges the implicit finality of the Bearer’s assertion.