If your subscription is not visible on the AskNebula website, it is likely because AskNebula web subscriptions cannot be managed through the App Store or Play Store. Website subscriptions are separate from mobile app subscriptions and are not displayed on your phone.
If you didn’t pay through Apple or Google, then your subscription might be for the AskNebula web service. Please refer to the articles below for more clarity:
If it's not related to the website, you might have a Lifetime subscription for the Nebula app. This provides the same premium features as a regular subscription, with the key difference being permanent access to all premium features.
Since this is classified as an in-app purchase and not a subscription, it doesn’t appear in your subscription list. However, all premium services should work correctly on your account, and you will no longer be charged.