not hear the end of sth

(will) not/never hear the end of sth AND
(will) not/never hear the last of sth {infml}
(to be told repeatedly about something; something that you say which means that someone will continue to talk about something they have achieved for a long time and in an annoying way) — будет бесконечно говорить об этом; ~ все уши прожужжит; заведется — не остановить

If you say you will never hear the end of it , you mean that someone is repeatedly going to speak proudly, criticize, etc. about something

Example 1: If Mary gets that promotion, we'll never/we won't hear the end of it (= she will talk about it for a long time). — Если она получит это повышение, она ж нам все уши прожужжит.

Example 2: We'll never hear the last of it if he wins that competition. — Да он нам все уши прожужжит, если победит. Он только об этом и будет говорить.

Example 3: Oooh! Don't get him started on this one, you'll never hear the bloody end of it! (kendo-world.com)

Related Vocabulary
[уши прожужжать]
[like a broken record]
[chew sb's ear off]