Star Sailors Redeem Codes

In-game: Tap the Menu icon (top-right) → Tap Account (Settings → Account) → Copy your CS Code (left side); tap the Redeem button → Enter the coupon code in the text field → Tap Use Coupon and collect rewards from the Mailbox. You can also redeem online on the official page (see the “How to redeem” section above). Codes are case-sensitive; each coupon once per CS Code. Rewards in the Mailbox (kept 7 days).

Usually because the code has expired, you've already redeemed it, or there's a typo when entering it.

Automatically every hour from official and trusted sources. Expired codes aren't deleted — they're archived into a database.