You can think of a binding as an energetic construct. So the question is how long does it take for the construct to be dissolved?
If a binding was a block of ice, it’s like you just asked, “how long does it take for the ice to melt?”
See the problem?
You need more information about the system the ice in in to answer that, and it’s different for different systems. In a chest freezer, it won’t melt, and if it’s in the oven at 350 degrees, it’ll melt in a few minutes.
If the binding is attacked by the target, the targets associates (human or otherwise) removed by you, or done in such a way that allows it to degrade, then over time it will go away.
If the target has no ability to remove it and you don’t, it won’t.
That said, you didn’t ask about just any old binding, you asked about Vovin’s Freezer Spell, and that is coded to expire:
If you read it, it’s in the wording of the spell. This is an example of what I mean by designing the binding to degenerate over time.
Write the problem persons name in full onto the piece of paper.
Roll the piece of paper into a scroll.
Bind the scroll with the piece of string and bind it tightly uttering your intent. “I want Marilyn Manson to stop meddling in my affairs and from saying or causing any harm to myself or reputation. May they become so embroiled in there own affairs that I will no longer be involved in any way with this person for as long as this string binds this scroll so mote it be.”
Take the bound scroll and put it into the pastic jar of water. Seal this and place it in the back of your freezer. The person should not bother you again… You can quite easliy undo it by thawing the frozen scroll and undoing the binding…
So the answer is, for this spell anyway, it will last as long as you don’t unbind the string, or the string does not rot. Which is probably why it’s in the freezer, so it doesn’t. If you moved and left it behind, it would likely get thrown out by the next person and then the string would rot in a landfill and the binding be undone.
I find it helpful with this that as you use your freezer you come across the jar and are reminded now and then that it’s still working.