As far as I'm aware, vMix doesn't support person to person license sales.

Which would mean that, no matter what you did, as the valid owner in the eye of vMix, you'd be able to cry "License hijacking!" to support and reclaim your license code.

I like that vMix Support is able and willing to aid victims of license hijacking, even if that means that they can't differentiate between legitimate victims of license hijacking and parties to sales that should never have happened in the first place.

When one decides to change jobs or move or even passes away, not everything in their possession can be sold.

This is one such item.

You bought it, you own it.

If you want to get rid of it, you can give it away, but pretty much any intelligent, rational person won't pay you for something that they know you can just take back on a whim without refunding their money.