Use every day, as many times as needed. For most people, it's best to use a moisturizer twice per day. In the morning, apply it before your sunscreen (or skip the moisturizer in the morning if your sunscreen feels hydrating enough). In the evening, a moisturizer is usually the last step of a routine.

Use your azelaic acid product every other day, either in the morning before your sunscreen or at night, before your moisturizer.