A friend of mine was collecting money to publish a sefer lzecher nishmas someone.
I said I’ll gave $50 or $100 (I don’t remember which) for the cause.
However he went ahead and published the sefer without asking me for the money.
I think perhaps he may have wanted larger donations and mine was too small (the people who donated have their names in the sefer) or maybe he forgot about me etc.
At the end of the day I didn’t give anything. Am I obligated to do something and is it considered a pledge?
Although the sefer was already published, money may still be needed for it’s publishing. Even if all the money was covered, you should still give the money either to someone else that is publishing a sefer and give it l’iluy nishmas, or you can give the money to a shul to buy seforim l’iluy nishmas the person.