You can easily share your purchases between devices as long as they use the same Apple or Google account. Here's how:
1) Install and open Just Ahead on your secondary device
2) Tap on Find a Guide
3) Tap on Manage Purchases (note: you'll have to scroll down to find the button)
4) Top the Restore button
5) You will be prompted for your Apple or Google password, enter it
6) After a few seconds any guides you have purchased from Apple or Google will appear on the screen
Once your purchases are restored you can now download and play your guides:
1) Tap the back button to return to the main screen
2) Tap Play a Guide, here you'll see a list of guides installed on your phone. To open the guide tap on the guide and follow the directions.
3) If the guide is not there Tap on Find a Guide, then tap on the guide you want to download, then press download
4) Once the guide is downloaded you can tap on it to open the guide
That's it!