Motor Life?

[Shark413]

Just wonndering, do brushless motors lose there magnetism over time? I know if you over heat them, they will lose their magnetism. But what about motors that are kept within specs, do they still lose their magnetism, just at a slower rate and over a longer period? And if they do lose magnetism how long do motors normally last? Is there a difference between highend (Neu) and bargin motors (Feigao) regarding how long they will produce acceptable power?