How long does it take for a moderate ankle sprain to recover? I have had a history of foot and ankle problems over the past 20 years.

4-6 weeks. Recovery times vary from person to person but 4-6 weeks is average. It is very important to rest and immobilize your ankle at first for proper recovery and ligament healing. I recommend you see a podiatrist for evaluation and treatment.
4-6 weeks. Usually 4-6 weeks needed for recovery from a "moderate" ankle sprain. Physical therapy can enhance your recovery. See your ortho doc. Good Luck.
Ankle sprain. Sounds like you have recurrent ankle sprains and you are in need of ankle stabilization repair which is surgical. I recommend you see a board certified foot and ankle specialist. Good luck.
4-6 weeks. The need for rest and immobilization is important for lower grade sprains. Higher grade sprains or chronic instability from previous injuries may require an MRI and possible surgical intervention.