Harry Potter and the Deathly Hallows Chapter 5

I never thought about this before but we are told here that Moody placed enchantments at the Order HQ. Now that Moody is dead, should the enchantments persist? When Dumbledore died, the petrificus totalus (or similar) spell he had placed on Harry died with him. Perhaps there are some types of spells that persist after the caster dies and some that don’t?

The more I think about it, the more I think there must be some kinds of magic that persist after the caster dies. Let’s take Hogwarts, for example. From the bewitched ceiling of the Great Hall to the singing suits of armor, magic abounds there. Do we really think all of those magical properties have been cast by living wizards?

There are three possibilities:

1. The spells end when the caster dies. Then another wizard must recast the spells to ensure minimum disruption. I think that unlikely and, if it were the case, probably lots of stuff would have gone haywire at the moment of Dumbledore’s death as I am certain that he cast quite a few ongoing spells there.
2. There is some sort of group spell casting thingy going on. It’s possible, I suppose, but we don’t have any indication of anything like that in the text.
3. There is a type of magic that does persist after the caster dies.

Let’s go even more specific and examine the entrance to the Chamber of Secrets. It was created hundreds of years ago by now-deceased Salazar Slytherin yet maintains its magic. This seems to rule out possibilities 1 and 2 as they would have required others to perpetuate the magic of the Chamber yet we are told that the Chamber has never been discovered by anyone since Slytherin’s death. Or possibly there has been a secret order at Hogwarts of Slytherin followers keeping up the magic of the Chamber continuously for hundreds of years – sounds like cool fan fic but I find it unlikely!

So I’m forced to conclude that 3 is the right possibility, that some forms of magic persist. I’m not sure of the exact taxonomy but perhaps these forms of persistent magic are called “enchantments” (vs spells, charms, hexes, jinxes, etc).

P.S. why are they so concerned with the timing of portkeys here? We know from the Triwizard Cup in Goblet of Fire that portkeys can be made without any temporal component.