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 Armenia.
There are no laws mandating alcohol vendors to ID potential underage drinkers. ID checks are very rarely, if ever, carried out Criminal Code the Republic of Armenia (2003), Article 166: Involvement, by a person who reached 18 years, of a child into regular use of alcohol drinks... is punished with correctional labor for up to 1 year, or with arrest for the term of 1-2 months, or with imprisonment for the term of 5 years
You can find more legal details and links here:
Wikipedia Legal Drinking Page