Open and historical orders can be viewed in Exchange PRO.
Active orders are limit orders that have not yet been executed, and are visible within the active orders tab (on your cell phone) or below the box (on your computer).

Active orders can be canceled at any time, free of charge. They also do not have an expiration date, meaning that they remain valid until the user who created them deletes them (by pressing cancel on the right side of the open order), or if a market transaction is executed at the price he stipulates.

In the latter case, the order will cease to be an active market order and will become a historic order.