Hello, 

I used to have my Steam version of Pathfinder Adventures linked with my iPad version. 

I got a new iPad and I have no more the old one. How can I unlink my devices to link my Steam version of the game with the new iPad ?

Best regards

Alef

Just use same user account in the new device. The game is bound to user account, not the spesific device.

As Hannibal mentioned, iOS linking is done with your Apple ID (specifically, the Game Center login), not any per-device method.

Just go to Settings --> Game Center, and check that your new iPad is logged into Game Center with the same Apple ID as the old iPad.  Relaunch pathfinder, and you should be be all set.  

Any further account problems can be sorted out with an email to support@obsidian.net.