Yes, it can be used in the morning, in the evening, or both, depending on how your skin tolerates the formula. The antioxidant pair of vitamin C (sodium ascorbyl phosphate and sea buckthorn hydrolate) and vitamin E (tocopheryl acetate) is often chosen for the morning because antioxidants help skin respond to city air, sun and other external stressors during the day. The formula also contains retinyl palmitate, a milder vitamin A derivative, which is frequently used at night for its renewing role. Neither choice is wrong; what matters is consistency and sun protection.
If you are new to vitamin C or vitamin A derivatives, start by applying the serum once a day, three times a week, rather than twice daily. After cleansing, apply a thin layer to face and neck and let it absorb for a minute before following with your usual moisturizer. In the morning, always finish with sunscreen — the serum itself is not a sunscreen and does not replace one. On days when you skip the serum, keep the rest of your routine gentle so the skin can adjust.