I am using a paid application (SwiftKey X Tablet) on my Vox. I got it from apktop.com, which hosts applications people pay for when they use android market. That's not my usual way of doing business, so I bought a copy using an old not-in-use device and then uninstalled it, so at least I paid the developer for it.
I also bought the paid version of LastPass on the LP website and I am using it just fine on the Vox.
If you buy on a rooted device, you can extract the apk files. Google is your friend.