They use the same network, so it should be fine. I think you'd need a new SIM card from T-Mobile--that should be pretty easy for them to answer if you call them.
It might not work. I had 2 metro pcs LG l9 and one Optimus F3 from metro. None worked on t-mobile without being unlocked. I know it's sounds crazy as metro is owned by t-mobile. But just my findings. My guess is its to sort of protect their customers from going to the other company