Does the pie need to be refrigerated I'd you plan to use that night or is room temp OK?

I would certainly refrigerate it, but it's worth pointing out that Key Lime pie (this recipe is simply a standard recipe for that pie with lemon/lime juice subbed for the key lime) was developed at a time when refrigeration was generally unavailable in South Florida, where it comes from. It also used meringue rather than whipped cream, however.

Yes, you definitely want to chill this pie before serving. ;o)

The instructions specify that the pie should be cold to slice....and considering the ingredients, I would serve it completely chilled.