Everyone eventually dies. However, death is a punishment in many cultures for radical crimes that are believed to be harmful to society, including the society of the ancient Roman Empire.
The images here, depict the deaths of the Greek philosopher Socrates, the Roman philosopher Seneca, and the Christians, Felicitas and Perpetua. These deaths all are the result of punishment for crimes against society.
Perpetua and Felicitas do not really commit suicide in the way that Socrates and Seneca do, however, they do sort of commit a kind of "noble suicide". Perpetua takes the sword of her executioner and brings it to her own throat as an act of killing herself for her crimes. Both Perpetua and Felicitas not only accept their punishments and crimes, but they are willing to take their own lives for their beliefs like Socrates and Seneca.