"Nepre" - from Russian "непременно". But in Russian we use it only in positive sentences. We can say: "я непременно куплю это" (mi nepre aĉetos ĝin), but we never say: "я непременно не куплю это" (mi nepre ne aĉetos ĝin). And it is used for some verbs and rarely used for anothers, but it is not so important. But I'm not sure it was inutually used in negative sentences like this sentence, maybe it's a sort of spoiled language
So would "Neniam ne parolu pri tiu afero!" mean "Never shouldn't [one] talk about that matter!"?
I typed the inferred "[one]", because there was no stated subject.
Or, in other words, "[One] should always talk about that matter!" ... à la the #MeToo movement.
Yay or nay? Aŭ, mi ne scias (se vi ne scias).