A method comprising: receiving , by a client-side computing device, a digital movie from a remote computing system, whereby a user authorized with the client-side computing device having purchased a limited license to access the digital movie; presenting, on a display, a visible code that, when detected by an optical sensor of the mobile computing device, causes the mobile computing device to initiate a sonic signal detection mode during which a microphone of the mobile computing device actively listens for sonic signals presented by the client-side computing device; periodically presenting , by the client-side computing device, sonic signals during presentation of the digital movie received from the remote computing system, the sonic signals being presented to confirm that the mobile computing device of the user authorized with the client-side computing device is within a desired geographic distance of the client-side computing device while the client-side computing device is presenting the digital movie received from the remote computing system, wherein each sonic signal is embedded in the digital movie, and each sonic signal, upon being detected by the mobile computing device, causes the mobile computing device to transmit a confirmation message to the remote computing system confirming that the mobile computing device detected the sonic signal; receiving , by the client-side computing device during the presentation of the digital movie, a notification that a number of unconfirmed sonic signals exceeds a threshold number of allowable unconfirmed sonic signals, wherein the number of unconfirmed sonic signals indicates a number of sonic signals presented by the client-side computing device that the mobile computing device did not confirm detecting; and in response to receiving the notification that the number of unconfirmed sonic signals exceeds the threshold number of allowable unconfirmed sonic signals, suspending the presentation of the digital movie. receiving , by a client-side computing device, a digital movie from a remote computing system, whereby a user authorized with the client-side computing device having purchased a limited license to access the digital movie; presenting, on a display, a visible code that, when detected by an optical sensor of the mobile computing device, causes the mobile computing device to initiate a sonic signal detection mode during which a microphone of the mobile computing device actively listens for sonic signals presented by the client-side computing device; periodically presenting , by the client-side computing device, sonic signals during presentation of the digital movie received from the remote computing system, the sonic signals being presented to confirm that the mobile computing device of the user authorized with the client-side computing device is within a desired geographic distance of the client-side computing device while the client-side computing device is presenting the digital movie received from the remote computing system, wherein each sonic signal is embedded in the digital movie, and each sonic signal, upon being detected by the mobile computing device, causes the mobile computing device to transmit a confirmation message to the remote computing system confirming that the mobile computing device detected the sonic signal; receiving , by the client-side computing device during the presentation of the digital movie, a notification that a number of unconfirmed sonic signals exceeds a threshold number of allowable unconfirmed sonic signals, wherein the number of unconfirmed sonic signals indicates a number of sonic signals presented by the client-side computing device that the mobile computing device did not confirm detecting; and in response to receiving the notification that the number of unconfirmed sonic signals exceeds the threshold number of allowable unconfirmed sonic signals, suspending the presentation of the digital movie. <EOS>