OSHA lists no set time but does state any worn, torn, or frayed, fall restraint system should be removed from use immediately. It is up to the user.
And as OldTimer stated they all are a ONE TIME use. Fall once go get a new one.

One nice thing about the Hunter Safety Systems which I do wear. If I fall I call them. I may not need to buy another vest according to the FAQs I read. And I use a LifeLine on all my tree stands which uses a Prusic knot. So I am tethered from the ground up on my ladder stands and any stand I use.

JW