You can check all purchases paid through your Zip account in your Singtel Dash app.
If you have any active orders, they will appear under the Upcoming payments tab. If you have completed the payment cycle for an order, it will appear under the Order History tab.
You can also view your current and past orders in the Customer Portal.
Under the Orders section in the Customer Portal, simply click on the View Order button and you will be able to see which instalments have been fully paid and which instalments are still outstanding.