Given the task definition and input, reply with output. In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.

Article: Children will find it more difficult to buy cigarettes as vending machines selling tobacco will be officially banned in England today.According to the British Heart Foundation(BHF),around 200,000 young people start smoking regularly in England each year and 11 per cent of l1-to15-year-old regular smokers in England and Wales get their cigarettes from vending machines. Betty McBride, Director of Policy and Communications at the British Heart Foundation,said,"Thousands of children who are at risk of addiction regularly get tobacco from these machines,which of course,don't ask them to prove their age.With the tobacco industry increasingly depending on young smokers to keep their profits,they're fighting tooth and nail to stop any changes that might hit their bottom line." The ban, which makes it illegal to sell tobacco from vending machines and requires shopkeepers to ensure all tobacco advertising on the machines is removed,comes into force in England today.It is the first ban in Europe to prohibit selling cigarettes from vending machines.which shows the determination of England to fight against smoking. Other measures to protect young people from the dangers of smoking are also on the way.In April 2013 large retailers in England and Scotland will have to get rid of all tobacco displays and small shops will be expected to do that from April 2015.Wales and Northern Ireland also plan to make similar regulations. The UK Government is due to begin a public consultation before the end of the year on whether to introduce plain packaging for cigarettes which would reduce their marketing appeal to young people,help to make health warnings more effective and,alongside other measures,help to reduce the number of smokers in the long term.
Answer: keep a record of every purchase
According to the text,vending machines selling cigarettes _ .