This is the main reason for the Mark of the beast.
While the MOB will be necessary to buy and sell, the purpose of the MOB is that it will be the identifying mark of those who have pledged their allegiance in worship of The Antichrist.
That is why there is no redemption possible for those who take the mark.
I think there will be something in that mark to track who has it. Today's technology has that ability through RFID.
Researchers announce a new passive RFID technology that uses ink instead of metals; the tattoos can be colored or invisible. They might help identify friend vs. foe.
www.livescience.com
The fact that a tracking system would be used says a lot about satan's limitations.
As much as satan wants to be "like God", he cant, and never will be.
God is Omniscient, All knowing.
Satan will enter The Antichrist but due to satan not being all knowing, a tracking system will be needed so The Antichrist will know who has taken the mark and who has not.