Either is possible. Extremely easy to give it three uses through 2da edits, but if you want to avoid that it's still doable.
Basically, whenever you finish resting you'd delete the integer called "layonhandsuses" and then whenever you use the spell you increment the uses of Lay on Hands if "layonhandsuses" is less than 2 and then increment "layonhandsuses." Would need to store the integer on an item the player possesses that they can't drop, ideally, so it's not reset if the player logs out.
Alternatively, you could set "layonhandsuses" to 2 and then increment Lay on Hands if it's greater than 0 which avoids the problem of it resetting if a player logs out -- but it does mean the player would then LOSE all uses if they get disconnected. So either way you'd want to store the data on a player item.
