It was a common joke a few years ago, when link shorteners were yet somewhat novel, to send someone a link, or post it on social media, with a story that would entice your target to click the link–which took them to the YouTube video of Rick Astley's Never Gonna Give You Up. Hence rolled to Rick, or Rick-rolled.
That's determination for you! All the same, I can't help instinctively writing "I shall" or "we shall" and getting it marked wrong every time. Can DL please accept that this is still correct, if somewhat old fashioned, British English? https://en.oxforddictionaries.com/usage/shall-or-will
maybe: Non ti lascerò mai d'andare via
"Non ti lascerò mai andare via" (without the preposition).
"I will never let you," as an answer to something like, "When will you let me sing?"
"Non te lo lascerò mai fare" (I will never let you do that) or "non te lo permetterò mai" ("permettere" = to allow).