When you log in to your Teammo account, your dashboard will always show upcoming games first, not games that occurred in the past.
However, if you need to pay for a game that occurred in the past (e.g. paying for it the day after), you can go to the 'Matches' page, which is accessible in the menu:
All unpaid games will be visible on this page. Scroll to the bottom of this page to find the game you want to pay for: