WALK THROUGH, Plaza Premium Lounge, Terminal 1, Toronto Pearson International Airport. 

Location is at airside at International Departures, Near Gate E77
Proceed towards the elevator ( FGP04) or stairs to reach Level 3.
Lounge is available from 5:30 am to 10 pm; if your flight falls outside of these hours, you won't be able to access it.
The maximum stay allowed is 2 hours, and children under 2 years old can enter for free.