See How to Determine Which Version of Plesk Control Panel is Installed on a Server to know which set of directions to follow.

1. Log into your Control Panel.
2. Choose the correct subscription from the drop down menu in the upper right.
3. Go to the Home tab.
4. Click on Domains and then [your domain name].
5. Your IP address is listed under your domain name in the white bar at the top of the screen.

1. Log into your Control Panel.
2. Choose the correct subscription from the drop down menu in the upper right.
3. Under Domains, click on [your domain name].
4. On the General tab, within the Hosting section is where your IP Address is identified.
   

Plesk 12.5:

1. Log into your Control Panel.
2. Choose the correct subscription from the drop down menu in the upper right.
3. Under Domains, click on [your domain name].