Yes, you can still get the key for free!
To get it you have to:
- First, login with Keychain to Dungeon Cities;
- Then, join the official Discord server and share your hive username in the channel called "hive-usernames".
In a few minutes/hours 
@blackheart1 will drop the key in your inventory on Dungeon Cities and you will be able to play the game for free :)
RE: [ENG/ITA] Dungeon Cities: Free Keys and My Experience So Far