Zest a lemon and lime until getting the required amount of zest. With a juicer, render the juice of the lemons and limes. In a medium bowl, put cream cheese and sugar together and blend. Add juice small amounts at a time to avoid splashing and to ease blending. Once the juice, cream cheese, sugar, and zest are blended, fold in the whipped topping.
Blend and then pour into the graham cracker crust (mixture will be slightly stiff). Smooth the top and cover.
Refrigerate for 1 hour. Then cut into either 6 or 8 servings. Can garnish with candied zest or gum drop citrus sections.