The poinsettias plant is a wonderful plant but sadly they don't stay alive very long even when you care for them properly.
You can expect a poinsettias plant to only last around 6 weeks or so before the flowers start falling off of them.
However in rare cases some poinsettias plants have lasted up to 6 months with proper care but it's unusual for them to last that long.
I love poinsettias but they just don't last as long as I wished they would but that's okay I still love them.