Well techinically they should enforce it if their website is correct:

http://www.aircanada.com/en/travelin...ges/index.html

"Age of Majority:

Please note that legal drinking age requirements are strictly enforced. Visitors under the age of majority will be granted access to the lounge only when accompanied by an adult with his/her own access. Adults who bring children into the lounge are kindly asked to supervise them."

Now the question is, is the age of 18 the age of majority in Ontario .. per this government website 18 is ... so you "should" be OK?

http://canada.justice.gc.ca/en/ps/sup/steps/s2c.html

Edited to add as per later posts that majority for drinking in Ontario is the age of 19 ... it has been sooo long