Methods are provided to authorize a secondary user device for a network service provided over a network. Responsive to receiving a request from a primary user device, a voucher may be transmitted over the network to the primary user device. A request for an authorization waiver may be received from the secondary user device over the network, wherein the request for the authorization waiver includes the voucher that was transmitted to the primary user device. Responsive to receiving the request from the secondary user device including the voucher, an authorization waiver may be transmitted to the secondary user device. Related methods of operating primary and secondary user devices are also discussed.