With proper care, cast iron pans can last for decades and even centuries, as cast iron cookware that is seasoned on a regular basis and cleaned after use is near impervious to damage.  Rust is the sole threat to cast iron pans, but even so, a pan that is rusted can still be rejuvenated in most cases.  It’s important to season cast iron cookware at regular intervals, as this will prevent damage and also create a nice non-stick surface on the inside and outside of the pan.  All cast iron cookware, including cast iron baking pans, grill pans, griddles, skillets, and Dutch ovens can be seasoned to preserve their condition. 

In addition to proper seasoning, it’s best to take a few steps to preserve the condition of cast iron cookware after it has been used.  Take these steps to care for cast iron pans following usage:

1.) Once the pan is cooled, wash it with dishwashing soap and water.  It’s important to never let cast iron pans just sit and soak up soapy water.  Once the washing is done, wipe the pan dry with a towel. 
2.) Following multiple uses, after washing the pan, place it on a heated burner for a minute or two to ensure it is dry.  While the pan is hot, oil the inside of the pan with vegetable oil, shortening, or lard.  Leave the pan on the burner for a few minutes, then remove and wipe off the excess oil with a towel.
3.) Store cast iron cookware with the lids off; if covered, moisture can build up inside and cause rust.  For extended storage, place a couple paper towels inside the pan that will absorb any moisture that forms. 

NOTE: these steps will also work to preserve the condition of cast iron biscuit pans, muffin pans, and baking pans, as well as Dutch ovens.

Now and then, the food cooked on cast iron grill pans or in cast iron Dutch ovens might start to have a metallic taste or turn black.  If this happens, it means the cast iron has not received sufficient seasoning, or that the food is being left in the pan after it has been cooked.  Never leave food inside a cast iron pan because the acids will break down the seasoning.  Move the prepared food to a serving dish or storage container as soon as possible. 

Note that nickel plated cast iron cookware isn’t affected by acids like standard cast iron cookware, and nickel plated cast iron pans can be used for simmering and food storage with no ill effects to the flavor of the food.  Nickel plated cast iron cookware is nonporous, and will never have an iron taste or retain the flavor of the last meal cooked inside.