Request for Refund – Purchased Wrong Stash Tab

Hello, I would like to request a refund for a Delirium stash tab that I accidentally purchased during the previous league. I recently found out that it’s possible to request a refund for mistaken purchases. However, since quite some time has already passed, I’m not sure if it’s still eligible for a refund. Could you please check and let me know if a refund is possible?

Thank you for your help.