While performing various tasks in Plesk clients use resources. For each client you can limit each specific resource usage. To edit the client’s resource limits:
Click the
Limits icon on the Client Home page. The Client limits page will appear containing the list of resource limit types: 
To set a limit value for a specific resource, uncheck the corresponding "Unlimited" checkbox and enter the value into the corresponding input field.
NOTE
The total limit on resources for the client must be more or equal to the total sum of the domain limits defined for the client.
At this page you can also set the period of validity for the given client account. To this effect, deselect the corresponding "Unlimited" checkbox, and define the desired date of account expiration in the Validity period input fields.
When you are done editing, click OK.