how can i turn it off ? i don t want to pay before i decide to do it !!
@nutttty - You can downgrade your membership at any time from the Account page (https://www.lingq.com/accounts/account/). This will cancel your subscription and will prevent any future payments from being taken.
so i have to do it one day before “the pay day” (the last day of my premium account ) 
? (because i don t want to turn it off now because i paid for one month)
@nutttty - Not to worry, while your subscription will be cancelled right away, your account won’t be downgraded to Free until the end of your current billing cycle.