Peugeot

Peugeot keys are decided by era. The older cars take a simple blade, while later ones use a flip remote with a transponder in the head, and the immobiliser system changed more than once across that span.

Read the part number off the original key where you have one, and confirm the year and the model. A blade cut to the right profile still will not start an immobilised car until the key has been programmed to it.