The plugin uses the following post meta keys to store invoice-specific settings: Meta Key Description Data Type _invoice_company_index Index of assigned company (references position in companies array) Integer or empty string _invoice_hide_files_until_paid Per-invoice override for file visibility (1 or 0) Integer _invoice_external_image_post_ids Array of attachment IDs stored in external storage Array of integers _invoice_external_file_map Mapping of attachment IDs to external file paths/URLs Array (ID => path) Option Name Description apie_invoice_numbering_config All invoice numbering settings (prefix, separators, padding, etc.) apie_enhancements_settings External upload enable/disable flag agency_pulse_companies JSON array of company profiles (shared with core plugin)