[kuschku]

Or easier:

If you're an EU citizen, just baksmali the Android App. As long as you don't copy code from their App decompiling is completely legal as per EU law there is no copyright on source code, but only on the implementation.

And for private use the API access will also be allowed.

Though I am not a lawyer, and this topic is still being discussed even in EU courts, so I wouldn't recommend using it for larger projects.