Rarely has a country taken an illegal drug overseen by a criminal organization and tried to replace it with the same crop produced legally, sold by corporations.

“Here we have an entirely new opportunity,” said Alejandro Gaviria, Colombia’s health minister, whose agency is issuing the licenses.

Mr. Gaviria said that decades of efforts by Colombia to move drug cultivators to other crops had hit a wall: The peasants made less money, rural development moved backward, and some farmers simply returned to drug cultivation.

“It’s been a complete failure,” he said.

Now, Mr. Gaviria argued, legal drugs could become an important economic tool for postconflict Colombia.

More than 220,000 people were killed as the rebels of the Revolutionary Armed Forces of Colombia, or the FARC, waged 52 years of war against paramilitary groups and the government, displacing the state entirely in some places. In the final decades, guerrillas moved into narcotics, financing the conflict through taxes on marijuana and cocaine, government officials and experts say.

The logic now: What if those profits were put into the hands of the government and peasants instead?

There is also a third actor that will profit greatly from the newly legal business, Canada’s PharmaCielo. Others, including a Colombian company, are seeking licenses, but PharmaCielo is the most prominent in pursuing cultivation in areas once controlled by the rebels.