As you can see in this marked part of code, there is a control switch named "Blessing Code Check" and if that switch is on you can't use blessing code anymore. That switch is OFF on the start of game and switches to ON when you use this code
So... you can use this code ONLY ONCE
But don't be sad, in Guide which is pinned on main page of game in itch.io you have all advice and tips how and where you can find more Goddess Coin