Migrating from device to device

I love this game, and hope to continue to play by purchasing platinum and keeping it going, but I have a very important (to me) question before I invest in that. I'm playing on a Moto Droid, but also own an iPod Touch, and hope to sometime in the future get an iPad. What I'd like to know is if I were to buy platinum on the Droid, does it tie the platinum and all purchases with the platinum to my account, or to my device? Like, after I get a dungeon set on my Droid, can I log into the game on my iPod touch and just play those dungeons, or will I have to pay again since it's a different device.

I'm a WoW player, and this would be like how I own the game and all expansions, and if the game is installed on any computer, I can play because I own the license to the game, which it tied to my account.

Please help me on this, because I want to buy the whole shebang, and maybe even a couple pieces of armor or vanity armor or something, but don't want to be screwed in the process. :) Thank you in advance to whomever answers this for me

All purchases are account based, and you can log on with your account from any device.

-ALS

thank you very much :) as I said, I plan on buying all the dungeon sets I can at the least :)