In a medium saucepan over medium heat, boil the pineapple and sugar 3 minutes. Mix in the lemon gelatin mix, stirring until dissolved. Stir in the cream cheese. Remove from heat and allow to cool 10 to 15 minutes.
Gently fold the apples, nuts, celery and whipped topping into the mixture. Transfer to a 9x9 inch square pan. Refrigerate 4 hours, or until firm.
