Boeing is planning to send six Starliner flights to the ISS after its certification. If it completes all six flights, this market resolves No. If it's announced that it won't fly all six flights, this market resolves Yes.

If it's announced that it will be terminated only after completing all six ISS visits, that doesn't count as Yes — they could still change their mind after though so it's not an immediate No either.

The initial test/certification flights do not count for the total of six.