My girlfriend took plan b one day before having unprotected sex. is she still protected? i've read there is a 5 day efficacy window of plan b?

It’s called the morning-after pill for a reason... Unlike regular birth control methods, which are used before or during sex, Plan B® is used after. The morning-after pill (AKA emergency contraception) can help prevent pregnancy when you take it after having unprotected sex. But, it won't prevent pregnancy for any sex you may have after taking it. ref: https://planb.ca/en/how-plan-b-works