The Austin said:
No, as long as you had the intention to keep it.
Best answer.
A bit of trivia & elaboration here: In the UK, police will arrest someone for theft under the following criteria:
Dishonestly appropriating another person's property with the intent of permanently depriving it.
If someone pinches a milk bottle off someone else at the time, with the intent to return it, because they honestly think that the other person would consent, or because they genuinely thought they had a right to it, then theft has not occurred. - It is only, if, at the time of stealing the aforementioned milk bottle, that they knew they were going to keep it for themselves & use it, then it is theft.
In exactly the same way, if someone makes a promise with the genuine intent of keeping it, but later finds that they cannot, then it is not a lie, just a promise that they didn't keep. If they made the promise, knowing that they wouldn't keep it, then it is definitely a lie.