"It is not for kings, O Lemuel, it is not for kings to drink wine,
or for rulers to desire STRONG drink."
This mother is not only teaching her son about inner virtue, strengths, and gifts but she's teaching him about status and social affairs; about checking his desires. There are some things that are not good for us to desire, because of the destiny on our lives. 1 Corinthians 10:23 says that some believe they can (and should) do anything. But it goes on to remind us that not everything is good for them to do. KINGS KNOW THE DIFFERENCE.
Gently reminding him of his calling, she's encouraging him to not drink. Strong drinks (rum, bourbon, tequila, gin, etc.) can cause you to become forgetful and unstable in your thinking. This is a position that rulers/leaders should NEVER find themselves in. Just because you're (finally) 21, or over 21 doesn't mean that you HAVE to go out and drink. It's always optional, and not mandatory, for you. Kings aren't common, kings don't do commonplace things and again, KINGS KNOW THE DIFFERENCE. Kings rise above.
So encourage and creatively remind your children today that though it may be social, some things are just not safe. Though it may be popular, some things are just not productive - especially for them. Teach your children to desire a positive perpetuity and contentment. It's okay for them to desire a balance. Proverbs 30:8 says, "...Give me neither poverty nor riches; feed me with the food that is needful for me". That's contentment.
Teach your children to always seek GOD'S desire for their lives (Matthew 6:33), above all others. What does God want for you? Let THAT become your desire and pursuit.