L'Aérobus is the shuttle service from Montréal - Pierre Elliott Trudeau International Airport to the Montréal Central Bus Station (Berri Terminal). Tickets for L'Aérobus are on sale at the Airport ticket kiosk. The Montréal Central Bus Station has direct access to Montréal métro (our subway), station Berri-UQAM. See map of métro.
We suggest you buy your public transport tickets or pass at Berri-UQAM. You'll save money and time. Consider taking advantage of the pass options (weekly or monthly) as they allow unlimited use of the buses and métro for the period. Ask for this at the kiosk, there is one in each métro station. Not at the airport, though (Montreal Public Transport Fares).