Your invoice number is emailed to you after purchasing an asset. All invoice numbers are numerical and contain up to nine digits. Forum registration requires a non-Behavior Designer addon pack invoice.
If you purchased via the Asset Store, this is a nine digit number beginning with 301, 302, 303, or a twelve digit number beginning with 01. If you do not have your emailed invoice anymore, you can locate your invoice number on on the Asset Store transactions page. This page will list the invoice numbers for all of your purchased assets. If you have any questions please contact email@example.com.