eBooks directly in an Android device:
I tested this proceedure on my Android 4.04 phone using the Aldiko Book Reader
Once you have made your purchase, the final receipt page will have a link to download your book. You will also receive the long form of the link in an order confirmation email.
This is important. If you don't already have one, get an Adobe user name and password to authorize the reader. Without authorization, once the book downloads and opens, it will be locked to that single device. Authorization registers the file to an owner and allows the book to be installed to multiple devices that use the same registration. You can register an Adobe account here.
Install the Aldiko Reader in your Android Device and run it. Upon installation it may prompt you to enter your adobe user name and password. If not, you can get to this by hitting your menu key, selecting setting, then selecting Adobe DRM.
Once authorized, go to the email receipt and copy the URL for the book. Now go back to Aldiko and you will copy it in to the "My Catalogs" section. You can access "My Catalogs" by selecting the Store icon at home page, after that, select the menu key of your device and then click the "My Catalogs" icon. Hit the "+" to add the URL. Enter a name then paste the link.
Open the URL from Aldiko app to download the files. After that, your downloaded eBooks will be automatically imported to your bookshelf in the app.