No expiration for now
Your Kodo points remain on your account until you redeem them in the Gift Gallery: there is currently no expiration date applied to your points balance.
Why this matters
You can therefore take your time accumulating points across several payments before exchanging them for a higher-value reward, without worrying about losing them in the meantime.
Should this rule ever change, Kodo would notify you beforehand in the app. If you're ever unsure about your balance, check the Activity tab or your profile, which always show your current points total.