Since embryos are people
Embryos can be single cells. The embryos we are talking about are about 10-20 undifferentiated cells. You kill more cells walking across the room.
And if they are people, then everything should be done to save them. Most of them die in nature, so we should spend billions on saving them.
do they change into non-people at 1-2-6-8 months?
By definition, frozen embryos do not develop over time. They are frozen. That is both literally and figuratively frozen. You cannot freeze humans, but there is no problems freezing a few human cells.