If the answer above is None it means there is no specific mention in the legislation, but you still need to ask local law enforcement before drinking in Lebanon.
Penal Code (1943), Articles 625-626 (promulgated by Legislative Decree No. 340 (2011) According to a global school health study, 40% of minors over 13 drink alcohol and up to 25% buy it from stores.
You can find more legal details and links here:
Wikipedia Legal Drinking Page