In a medium mixing bowl, use a handheld mixer on medium-high speed to beat the cream cheese, sweetened condensed milk, thawed lemonade concentrate, and lemon extract for 1½ to 2 minutes until smooth.
Reduce mixer speed to low and add the lemon instant pudding mix.
Increase speed to medium and mix for 1 to 1½ minutes until the mixture is smooth and begins to thicken.
Gently fold in the whipped topping until fully combined.
Spread the filling evenly into the premade graham cracker crust.
Cover and refrigerate for at least 8 hours before serving.