"For an adventure, you do not necessarily have to pay."
Translation:Por aventuro oni ne nepre devas pagi.
Is nepre really a good choice here? I understand it to mean definite. Seems to me nepre would make it "For an adventure, you definitely don't need to pay."
It's something like "unavoidably, obligatorily".
Note the position of the negation, though -- it's not "oni nepre ne devas pagi" (which would be more or less your interpretation) but "oni ne nepre devas pagi" (which turns it into something like "you not-obligatorily have to pay" or "not necessarily have to pay"
This sentance translate as "For an adventure, you don't need to pay", which leaves out the necessary from the original sentance