how often should I use granactive retinoid?

It's better to not use it every night from your first use retinol can easily irritate the skin, start with twice a week for at least two weeks then increase the times to 3 or 4 times a week if you see that your skin can handle it. Also refrigerating retinols and other Vitamin A derivatives can extend their shelf life and prevent accidental heat and light exposure since light and heat exposure is damaging to all retinoids, it can safely be stored at room temperature but to prevent any damage to the product specially in hot temperatures and sunny places refrigerating it is safer.

If your skin is acclimated to it then you can use it every night. But if this is your first time incorporating retinol into your skin care routine, you should use retinol every other night just so your skin doesn't get irritated.

Better start slowly , using it on each day. To prevent skin irritation. But if ur skin can tolerate it while using every night , then u can go. I thought using this serum with sandwich method is a good way to decreased irritation probability , of u wanna use this every night .

If it’s ur first time with retinol u can try to incorporate that once or twice a week and then slowly increase Storing that in fridge can be useful to extend the shelf life, but it’s not essential, so if u don’t want to do it, it’s totally fine

As you have just started, I would start slower at maybe once or twice a week, and build up tolerance - this can help reduce the purging and irriation you may face. You can slowly build up the days once you feel your skin is ready! Make sure to observe your skin carefully and feed it plenty of hydration. You don’t have to refrigerate the product, it was made to be fine to store and use in the average temperature. Just keep it in a dark place, preferably kind of cool.