How long does a ghoul paralysis last in 1st edition Advanced Dungeons & Dragons? That depends on what book you look in.
Older editions of Dungeon & Dragons have many odd quirks. Many finds these idiosyncrasies endearing, while others find them frustrating. One of those quirks is that information on how an item, spell, monster ability, etc. functions is often spread out through the text of a book, or in multiple books. A specific quirk in the first edition of Advanced Dungeons & Dragons is the duration of ghoul paralysis. It seems that this was left out of the Monster Manual, and has vexed Dungeons Masters for the last 40 years. However, the duration was addressed on a number of occasions, in a number of books. They are:
1. The module, T1 The Village of Hommlet (1979), lists it as 3-12 turns.
2. Sage Advice from Dragon #37 (May 1980) lists it 24 hours or each DM should decide.
3. Sage Advice from Dragon #39 (July 1980) lists it 3-12 turns.
4. Advanced Dungeons & Dragons Monster Cards, Set 1 (1982), lists it as 2-12 turns.
5. The article, “A Touch of Evil”, in Dragon #126 (October 1987) lists it as 2-12 rounds.
6. REF 5 Lords of Darkness (1988) has this to say about it: “The duration of the paralyzation depends on the victim’s Constitution. Subtract the victim’s Constitution from 20 and add 1d6 if the attacker is a ghoul and 2d6 if the attacker is a ghast. The result is the number of rounds that the paralysis lasts."
By comparison, other editions of D&D list the duration differently.
1. Original D&D “brown books” (1974), no duration listed.
2. “Basic Rules” D&D “Holmes version” (1977), no duration listed.
3. “Basic Rules” D&D “Moldvay version” (1981) lists it as 2-8 turns.
3. “Basic Rules” D&D “Metzger version” (1983) lists it as 2-8 turns.
4. Second edition AD&D lists it as 3-8 rounds.
5. While it never directly addressed in Dispel Confusion, in Polyhedron #2 (Autumn 1981) it does note that the carrion crawler paralysis (the MM also does not list the duration of its paralysis) has the duration of a wand of paralyzation, i.e. 5-20 rounds. I think this would be similar for ghoul touch.
For AD&D there seems to three different, contradictory “official” rulings on the duration of ghoul paralysis (note #1, #4, and #6 on the first list). The Dragon magazine Sage Advice articles are not considered “official” rulings for AD&D, but can give some insight. This leaves a Dungeon Master in a conundrum about which ruling is best. In the end, I think it is your call to decide which works best for your game.