Since you’re doing something the rules don’t cover, there is no rule that tells you one way or the other how it’s “supposed” to go – it’s up to you.
I would recommend not having it be a single save ever, since that would mean someone who makes the save never has to worry about that effect ever again, while someone who does not can never break it.
Personally, I would probably rule it like this:
Each time you attempt to lie within the temple, you must make a Will save. If you fail, you cannot tell that lie, nor any other lie for the next 24 hours. If you succeed, you may tell the lie, but must save again the next time you want to tell a lie.
I’m not sure exactly what I’d call “one lie” – perhaps a lie, once established on a successful save and Bluff check, can be freely spoken, but introducing another false “fact” requires a save. Or perhaps it’s a save per attempted Bluff check, but a single Bluff check may involve several lies. It would depend on how powerful I want the effect to be, and how much I found constant rolling/keeping track of what is a separate lie to be annoying and slowing down the game.
Though, with something like this, I’d also just consider waiving the saving throw altogether. It’s a plot point, after all. I’d allow things like mind blank, and perhaps misdirection or nondetection, foil it, but otherwise I wouldn’t allow a save if the temple really is supposed to be famed for this effect. Otherwise a minimum of 5% of attempted liars would be able to tell at least one lie in the temple.