Deep, long-standing cracks in the feet are usually due to very dry skin, pressure on the heels, or conditions like Plantar keratoderma or even fungal infection, and they tend to recur if only short-term creams are used. The best long-term approach is consistent care, apply thick moisturizers containing urea or lactic acid twice daily, especially after bathing, gently remove hard skin with a pumice stone (not aggressively), and always wear cushioned, closed footwear (avoid walking barefoot). Keeping the feet clean and dry, using heel pads, and treating any underlying infection or medical condition (like diabetes or thyroid issues) is also important. If cracks are very deep, painful, or not improving despite these measures, consult a dermatologist or podiatrist, as you may need stronger prescription creams or protective dressings to allow proper healing.