When you buy a Kindle you get an email address for it (find it in your Amazon account in the device information section). You can add that email address to Calibre and just email the pirated books to it. It will auto-convert to the appropriate format (though they keep on sending me an email saying this is going away) and keep it in your Amazon cloud library. That way the books don't have to stay on the device and you can download them to any Kindle you own in the future or anywhere you have the Kindle app installed.
When you buy a Kindle you get an email address for it (find it in your Amazon account in the device information section). You can add that email address to Calibre and just email the pirated books to it. It will auto-convert to the appropriate format (though they keep on sending me an email saying this is going away) and keep it in your Amazon cloud library. That way the books don't have to stay on the device and you can download them to any Kindle you own in the future or anywhere you have the Kindle app installed.