Frozen foods, including cookies, remain safe to eat as long as the temperature does not rise above 0 degrees F according to the University of Missouri's guidelines for freezing home prepared foods.
Flavor and Freshness
While cookies frozen for long periods of time remain safe to eat, their flavor can deteriorate over time. The cookies may also develop freezer burn over time which will affect both the flavor and texture.
Enjoy your frozen baked cookies within three months to ensure that they still taste as good as when they were fresh.