Could you please advise me on pricing for mutliple users, devices?

There is not pricing for multiple users. If you have multiple users, and you want to upgrade them all, you will have to buy a subscription per each user: https://www.jotform.com/pricing 

If you upgrade only one account, you can share your forms with the other users, depending on the sub-user accounts your account let's you add.

Please note that adding an account under yours as a "sub-user" does not mean "inheriting benefits".

This feature is just to be able to share your forms with someone else's account, and grant them different access to your forms: https://www.jotform.com/help/232-How-to-Share-Forms-with-a-Sub-account-User 

Let us know if you have more questions.