You can find this section in HostBill Admin → Settings → Products & Services → Your order page → Your product → Other Settings
Use this option if you want limit instances of this product for each client account. If enabled clients will not be able to order more than specified limit.
This option controls whether your customers will be able to cancel their order. You can:
If can enable your customers to make upgrades. From the available product list on the left select product that you wan to offer as an upgrade to this package and move it to the list on the right.
If you want to disable upgrade option, select it on Applied products list and click on button.
Those changes require you to save product configuration.