The maximum amount of tickets that can be purchased per game will never exceed 300. However this limit does not come into effect when buying for more than one game. For example you can buy 100 tickets for all 5 games (totalling 500) that play within a session as this is essentially multiple game play and you will be within the limits set by a game by game basis.
Players can usually buy any number of tickets up to a maximum per game, but there might be games where all players can only buy the same amount of tickets. Occasionally, there might be free games, where all players receive the same amount of free tickets (free-of-charge games), or some players might receive free tickets that can only be played on certain games (promotional tickets, free tickets).