To check for the current version use the following command line
Version 15.0 (Build 516.32)
Get-Exchangeserver | ft Name,Admin* -Autosize
How to upgrade your existing Exchange Server 2013 to CU7 using command-line
You will have to download CU7 pack, extract it and run the command line from CMD with administrative privileges.
Here we run the CMD as admin
Drag and drop the folder you extracted into CMD window to be able to enter into the path in order to run the setup file.
Run the following command to upgrade the existent server
Setup /Mode:Upgrade /IAcceptExchangeServerLicenseTerms
Below you can see the upgrade process to install the Cumulative Update 3.
Once the upgrade process is finished you will be able to see the new version in the cmdlet after you apply the cmdlet
Get-ExchangeServer | ft Name,Admin* -AutoSize
The version must show 15.00.1044.025