negative levels

[Nik the fan]

Hello, i was hit by a vampire spawn. On the stat block is presented as follows

"Energy Drain (Su)
A creature hit by a vampire spawn’s slam (or other natural weapon) gains one negative level. This ability only triggers once per round, regardless of the number of attacks a vampire spawn makes."

there is also this from gamemastering --> special abilities:
"Energy Drain and Negative Levels:
Some spells and a number of undead creatures have the ability to drain away life and energy; this dreadful attack results in “negative levels.” These cause a character to take a number of penalties.
For each negative level a creature has, it takes a cumulative –1 penalty on all ability checks, attack rolls, combat maneuver checks, Combat Maneuver Defense, saving throws, and skill checks. In addition, the creature reduces its current and total hit points by 5 for each negative level it possesses. The creature is also treated as one level lower for the purpose of level-dependent variables (such as spellcasting) for each negative level possessed. Spellcasters do not lose any prepared spells or slots as a result of negative levels. If a creature’s negative levels equal or exceed its total Hit Dice, it dies.
A creature with temporary negative levels receives a new saving throw to remove the negative level each day. The DC of this save is the same as the effect that caused the negative levels."

and finally this from monsters rules:

Energy Drain (Su)*

This attack saps a living opponent’s vital energy and happens automatically when a melee or ranged attack hits. Each successful energy drain bestows one or more negative levels (the creature’s description specifies how many). If an attack that includes an energy drain scores a critical hit, it bestows twice the listed number of negative levels. Unless otherwise specified in the creature’s description, a draining creature gains 5 temporary hit points for each negative level it bestows on an opponent. These temporary hit points last for a maximum of 1 hour. Negative levels remain until 24 hours have passed or until they are removed with a spell such as restoration. If a negative level is not removed before 24 hours have passed, the affected creature must attempt a Fortitude save (DC 10 + 1/2 the draining creature’s racial HD + the draining creature’s Cha modifier; the exact DC is given in the creature’s descriptive text). On a success, the negative level goes away with no harm to the creature. On a failure, the negative level becomes permanent. A separate saving throw is required for each negative level.

So, are they permanent after 24 hours and a failed save or not?

[Artofregicide]

Yes, under normal circumstances.

[Bacondale]

It's confusing as it states that you get a saving throw each day in one section and that the negative level becomes permanent after one day and a failed save in another section.

The daily saving throw only applies to "temporary" negative levels. In the case of the Energy Drain monster ability, the "temporary" level becomes a "permanent" negative level after the first failed daily save and "permanent" negative levels do not get a daily save.

[Diego Rossi]

EssentiallY: energy drain (SU) becomes permanent after you fail the save you make 24 hours after receiving it. Several spells that give you negative levels work the same way.
Some forms of negative levels are temporary and can be saved day after day (or end after a set time), but they are the minority.

It would have been way more simple to say that if the save you make after 24 hours the negative level become permanent unless the attack specifies differently.