It does say those who have the mark may buy and sell. Nothing is said about the mark being given for worship.
Satan is allowed to kill any who do not worship him.
"And he had power to give life unto the image of the beast, that the image of the beast should both speak, and cause that as many as would not worship the image of the beast should be killed."
You could have the mark, to buy and sell, economics. But even with the mark, if you did not worship, you could still be killed.
However having the mark, but being killed for not worshiping will still place you ultimately into the LOF.
The only way to avoid worshipping, and the mark, is to just get it done and over with, and that is a beheading.
This period is only during the 42 months leading up to the 7vials (wrath of God) Armageddon. The vials are poured out in the 3 days after the 42 months are over. When the 2 witnesses are killed and left for dead, that marks the same 3 day period between the 42 months and Armageddon. The 6th vial is the gathering of all humanity against Christ the King at Armageddon.
"And the sixth angel poured out his vial upon the great river Euphrates; and the water thereof was dried up, that the way of the kings of the east might be prepared. And I saw three unclean spirits like frogs come out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet. For they are the spirits of devils, working miracles, which go forth unto the kings of the earth and of the whole world, to gather them to the battle of that great day of God Almighty. Behold, I come as a thief. Blessed is he that watcheth, and keepeth his garments, lest he walk naked, and they see his shame. And he gathered them together into a place called in the Hebrew tongue Armageddon."