Transferring a subscription means that the ownership of a subscription changes. It reassigns a subscription of another user to either another customer or yourself.
1) To do this, go to Subscriptions.
2) Choose a subscription.
3) Click Change Subscriber.
4) Select the new owner.
5) Then click Next.
6) Review the new subscriber's information and scroll down to the bottom.
7) Click Finish.
That's it! Now you know how to change the ownership of a subscription in Plesk.