First of all, you need to turn on price crowdsourcing under settings (only done once).

Tap the shopping list item in question, e.g. apples.

Then tap the name field to expand additional detail fields and enter the weight and unit you are buying.

Set the unit to the unit that the price is given for, e.g. if price is per kg then enter how many kg you buy.

A toggle will appear just above the note field that lets you toggle ON price per unit.

If you go back to your list, you can see that the line reflects the price (per unit) and that the total price row at the bottom of the list now reflects the amount x weight x price

No, your premium subscription is pre-paid and non-refundable.  In general Grosh is try-before-you-buy with the vast majority of features being available in the free version, see also this premium app overview. The primary motivation for purchasing premium should be that you want to support the continued development of the app, and secondarily to get a handful of extra features. If you want to retract your support to us or for some other reason request a refund, then you should not contact us directly. We cannot refund as you actually bought the premium subscription from Apple or Google, see this FAQ entry.

If you’re logged into the app, choose Logout under Settings. On the login screen, press “Forgotten password”, enter your email and we will send you an e-mail with a link to reset your password. Through this link, you can choose a new password. Use that password to login from the various devices where you installed Grosh.

Yes, you can assign priority to shopping list items by tapping details, then tap the item name to make additional detail fields visible. One of them is the “Important” toggle switch. When this is ON, you will see a exclamation mark marking on the shopping list. You can tap the exclamation mark to filter / unfiltered the list. Also check out this blog post.

Yes, but this requires that you setup email / password for your account and use that from all the devices that should login to your account.

Note: If you just tap continue on the last intro page instead of tapping Have an account? you’re not logging into your account using email /password. What actually happens behind the scenes is that you login using the so-called device id associated with the device. When you login using your device id, you will log out any other devices using email / password credentials. If you happened to do this by mistake, you can always logout from Settings, choose to reset your password on the Login screen – and then login using email/password.