How to change the expiration date for a subscription in Plesk?
Note: Service Provider view has to be enabled in order to manage subscriptions. If you do not have Service Provider view, check the solution for Web Admin edition below.
Go to Subscriptions > example.com > click on upper-right icon to open the right navigation pane > Customize.
On the Resources tab, set up the Expiration date.
Click Update & Lock. The subscription will be locked from further changes in its service plan.
Note: To change the expiration date for all subscriptions under a service plan, go to Service Plans > plan_name > Resources.