if I understood your question correctly, you would like to register the Webex Desk Pro to the customer's CUCM or Expressway environment.
As @Nithin Eluvathingal has written, you or somebody from your company should have received an email from Cisco stating the licenses need to be provisioned. If you have not received it, then you can get in touch with the team that placed the order in CCW tool. There they can resend the email and also change the recipient (e.g. to your email address).
After the provisioning is completed, the on-premises licenses will be sent to the Smart Account of the customer (which was provided at the time of the order). Within the Smart Account it might be necessary to move the licenses to the correct Virtual Account, if not using the default one.
You will receive a provisioning mail from Cisco, once you complete the provisioning, the license will be available on your Smart account.
If the partner who sold already mentioned the start date, the subscription will be automatically activated on the start date mentioned on the order and all licenses related to your order will be available on your smart account.
Kindly reach out to the partner if you haven't received the provisioning mail or to activate the subscription.