Make sure you're logged into itch.io with the same email you used to buy it. If it still doesn't show up, try using the "Recover Purchases" field on this itch support page: https://itch.io/support
Make sure you're logged into itch.io with the same email you used to buy it. If it still doesn't show up, try using the "Recover Purchases" field on this itch support page: https://itch.io/support