The dev used GamerSafe for paid content support (premium) - which shut down sometime this month. http://gameinabottle.com/blog/2017/02/gc-labyrinth-premium-is-free-to-play-now-on-gameinabottle-com/
The game (with premium) is now avaible here: http://gameinabottle.com/gcl.php
 "GemCraft Labyrinth"){kind=icon}