CARACAS (Reuters) – Two Iranian tankers that delivered fuel to Venezuela as part of a five-vessel flotilla have begun to sail back, according to Refinitiv Eikon, as the government of the South American nation prepares stations to begin charging for the gasoline.

The supply is meant to ease fuel shortages that have plagued the country. After three months of fuel rationing, Venezuelans began lining up on Saturday to wait for the Iranian gasoline to be sold at stations from Monday under a new system combining subsidies and internationally-indexed prices.

The model will put an end to over two decades of Venezuelans filling up their tanks for next to nothing.

The two first Iranian tankers that discharged fuel last week departed over the weekend from state-run PDVSA’s ports. The Fortune on Sunday set sail to its origin port, Iran’s Bandar Abbas, with estimated arrival in July, while the Forest on Saturday departed from the Cardon refinery before switching off its satellite signal, according to the Eikon data.

As both nations are under U.S. sanctions, Washington is monitoring the supply while warning governments, seaports, shippers and insurers that they could face measures if they aid the tankers.

In most of the country’s 1,800 gasoline stations, motorists will be able to buy 60 to 120 liters per month at a subsidized price of about 2.5 U.S. cents per liter. After surpassing quotas, tanks will be filled at higher prices. Details of the new model, including some final prices, have not yet been revealed.

Venezuela’s oil minister Tareck El Aissami said on Sunday that licenses were approved for 200 stations to sell gasoline at internationally-indexed prices without quotas. The initial price at those sites is $0.50 per liter.

“To the people: thank you for your comprehension, for your heroic resistance and for trusting President (Nicolas) Maduro’s government,” he said in a televised speech.