You will be able to download the CookBook app onto different devices for no extra charge if they are on the same platform (i.e Apple or Android) and if you login to the iOS App Store/Google Play Store using the same app store login.
You would need to buy the application on both Apple iOS and Android if you have devices on both platforms and if you have different app store accounts on the devices.
Please note that as the Apple App Store and Google Play Store are run by different companies, we have no means of sharing the purchase licence between them.
Once you have the app on all devices you can simply login using your CookBook account login details.
Additional Android tips:
If you access the Play Store, click on the menu button (top left) and click ''My apps & games" at the top. This will let you see all of the apps you have purchased and you can then download them again on new devices. Note that you must be logged into the same Google Play account that the app was purchased from.
You can see more information here at AC; https://www.androidcentral.com/ask-ac-can-i-install-android-apps-more-one-device
Please note the only thing you cannot share across different devices is the shopping list - this is something we plan to change in a future update so that it will sync across devices too!