I believe that all Trade Goods effects are global, and once built, can only be acquired by barter, or by conquering the original planet the good was built on. When bartered, the receiving race gets the benefit immediately (they don't need to build anything), and I don't think anything can take it away from them.
Which gives rise to an interesting followup question: If you build a Trade Good, and the planet it was built on is abandoned or conquered, do you retain the bonus, as though you'd traded it to yourself?