Promises should not be trusted.
The first recorded use of this expression is by Ridens on Aug 16, 1681:
"He makes no more of breaking Acts of Parliaments, than if they were like Promises and Pie-crust, made to be broken."
The internet has little in the way of information on the life of Heracl*tus Ridens but a glance at his writings shows him to have been an essayist, poet and satirist. The chances are that he was named for the pre-Socratic Greek philosopher Heracl*tus of Ephesus.
Irish writer and satirist Jonathan Swift, however, popularized the expression in his 1738 book, Polite Conversation, and thus is often attributed with being the author of it:
Lady Smart: Ay, thou has a head and so has a pin. But my lord, all the town has it that Miss Caper is to be married to Sir Peter Giball; one thing is certain that she hath promis'd to have him.
Lord Sparkish: Why, Madam, you know promises are either broken or kept.
Lady A: I beg your pardon, my Lords, promises and pie-crust are made to be broken.
Polite Conversation consists of three satirical dialogues presented as a guide to "Genteel and Ingenious Conversation, According to the Most Polite Mode and Method Now Used at Court, and in the Best Companies of England". Some critics view the dialogues as transcripts of actual speech (albeit presumably somewhat honed in order to flow as complete dialogues).
