To hold one accountable for a commitment, make good on a promise.
You made a fair bet with me on the Superbowl and I am going to hold your feet to the fire for payment.
Pertains to torture used during the Crusade's. As a method for extracting confession for heresy, non-believers were positioned in a manner that allowed the inquisitor to apply flames to the feet of the accused. This was done until the accused confessed or died.
As ridiculous as that method of obtaining a confession seems by today's standards, consider a modern parallel - plea bargaining. The accused is offered the choice between a reduced sentence in exchange for a confession, or prosecution with the risk of more severe penalty (possibly death).