Are you still protected the first day of hormone pills you take after the placebo week?
Hormone pills are NOT necessarily birth control pills, so you
should make sure that it is intended for the correct usage. And no,
you can't get pregnant on the last week of the inactive pills,
you've already been taking three weeks of the active pills by then,
which is why those pills are for the last week of your cycle; which
usually are some sort of iron supplement.