In simple terms, it does decay, then immediately recombines.
When a neutron decays it makes two charged particles. But inside a neutron star those two charged particles (proton and electron) have no room to separate, instead, because they attract each other they immediately recombine.
Normally they can not recombine because of the energy gap - they need some extra energy to become a neutron (which is why hydrogen, which is also a proton and an electron doesn't just turn into a neutron).
But inside a neutron star that energy is not lost, instead it's transfered to some other set of protons and electrons, giving them the energy they need to become neutrons.
When a neutron decays it makes two charged particles. But inside a neutron star those two charged particles (proton and electron) have no room to separate, instead, because they attract each other they immediately recombine.
Normally they can not recombine because of the energy gap - they need some extra energy to become a neutron (which is why hydrogen, which is also a proton and an electron doesn't just turn into a neutron).
But inside a neutron star that energy is not lost, instead it's transfered to some other set of protons and electrons, giving them the energy they need to become neutrons.