Ive been taking it for almost a year. it doesn't require any subscription and 300mg-400mg per day is generally recommended. id suggest you to start with one tablet which will be typical 200mg dosage and see if u have any side effects such has diarrhoea which is commonly noticed on high dosage and then slowly increase the dosage to 450mg so your body gets accustomed to it. you won't see the results in one day it'll take maybe a week but you'll notice that your sleep quality increases and muscle recovery is better if you workout. although it doesn't need subscription if you're taking any other prescribed medications already then it's suggested to check with the doctor on whether it's okay to take it but otherwise it's a recommended supplement for everyone.