A single subscription of Office 365 ProPlus allows you to install Office 365 on up to 5 devices.
Office 365 ProPlus includes a fully functional, cloud-based online version that is free to use, though it does not require any installation.
Incorrect Answers:
Office 365 subscriptions (E3, E5, etc.) do not allow for downgrading.
Office 365 ProPlus is updates automatically. Updates include updates to existing features as well as new features being added to the product.
Reference:
https://xo.xello.com.au/blog/office-365-proplus-top-business-benefits-for-users
https://support.office.com/en-us/article/what-s-new-in-office-online-fc1de049-98f3-46da-a5aa-da4a19c3e909?ui=en-US&rs=en-US&ad=US