Finding the Platform Server version
The Platform Server version can be found in both Lifetime and Service Center applications.
Lifetime is accessible via http://<lifetime_environment_domain>/Lifetime/ and there you can find the version information in the page's footer:
In Service Center
Service Center is accessible via http://<any_environment_url>/ServiceCenter/ and there the version information is visible on the right-side panel:
Finding the development tools' version
To determine your Service Studio version, open Service Studio and, on the menu, click on "Help" » "About":
To determine your Integration Studio version, open Integration Studio and, on the menu, click on "Help" » "About":