Here in BC, the last person to shoot an animal is the person who killed it and had better have a tag.
Just such a witnessed kill on a bull moose, ended up with the game warden charging the fellow who put the last bullet into the animal & killing it and not punching HIS tag. The fellow who first shot the moose, had cut his tag, so according to the law here, he had already shot "his" moose, prior to this one.
Tags have dates, months and days and must have the proper date punched out immediately upon killing the animal, before any butchering is done.
How this works with guiding hunts, I do not know, as the guide oft times, is the last person to shoot an animal.
This only happened to me once, on a bear.