First, check that your NoteAI subscription is active in the store account used for the purchase and make sure you are signed in to the correct NoteAI account.
Update and reopen NoteAI, then use Restore Purchase in Settings. Read the message shown when a feature is unavailable. A usage-limit message may mean you have used your current allowance, even with Pro access. A processing error may require a different troubleshooting step.
If the issue continues, contact our support team with the feature name, error message, app version, device type, and purchase reference.