Mathematically speaking entanglement is local: in entangled state |11>|22>+|12>|21> the state |11> coexists with |22> and not with |21>, so when the particles f

Mathematically speaking entanglement is local: in entangled state |11>|22>+|12>|21> the state |11> coexists with |22> and not with |21>, so when the particles fly away and meet again, |11> still meets with |22>, it's sealed at the time of creation of the state.