All opt-in lists and lists of numbers that have opted-out of a keyword are stored on the TextPower servers and are accessible only to people with appropriate credentials.
Credentialed users can access the opt-in lists either through the AlertManager web app or by downloading a list of opt-ins for that keyword from the customer portal. Login to the customer portal here:
Opt-in and opt-out lists can be accessed through the TextPower portal. Login and go to the menu item Campaigns>Up/Download Opt-ins/Opt-outs. Choose the keyword for which you want to download a list of numbers and follow the instructions to download a file that will contain all of the cell phone numbers that are opted-in or have been opted-out to or from that keyword.