Where do additional-usage charges appear on my invoice?

As separate rows on your normal Deskhero invoice, for example "120 additional tickets at $0.05 each", with the quantity and the rate you approved, plus a row for extended retention if you use it. Additional usage is calculated after the calendar month (UTC) has ended, so it can appear on a later invoice than that month's subscription. For workspaces billed through Shopify, a completed month's additional usage is added once to a following Shopify statement. Usage above the included allowance is only charged when an owner or admin has approved it, and never beyond the approved maximum.