All you need to do is mantain a balance of at least 30,000 satoshi (0.0003 BTC) in your FreeBitco.in account and we shall pay you compounded interest on your full balance everyday. There is no lock-in period to earn interest (you start earning interest right from the first day!) and your balance can be withdrawn any time you wish. Treat your FreeBitco.in account like an instant-access savings account to hold your excess bitcoins and earn passive interest on your account balance everyday.