The possible endings is- to conquer all the squares, research a cure in the lab, take control of the city hall and to close the portal in the evil graveyarde.
Do not give up just because you do not have the Premium Edition. You can Still Win the Game and Have plenty of fun. I Have just complete Gemcraft Labyrinth Without the Premium Edition and thats was no waste of time! Don't forget to chance priority to fewest hit point to reduce banicment , unlock gems and sacrofice gems in the anvil to extract mana. The best gems is Blooudbound gem, Multiple Damage gem and Armour Tearing gem.