What does it mean to buy AJ lottery numbers? I won't. Do I have to buy it?

In recent years, AJ goods are in short supply, so every store sells them by lottery. For example, 100 pairs of shoes are issued, but 1000 people buy them, so this 1000 people need to draw lots, and then randomly select 1000 people from this1000 people, and the person who gets the number will buy them. If you get the number, you can not buy it as a waiver and let others buy it.