How to Activate Exchange Server 2013 ~ System Help Line

Follow the below steps to activate your Exchange Server 2013

Login into Exchange Admin Center ( read this to know how : How To Access Exchange Admin Center in Exchange Server 2013 ) and then from the left side menu, click on servers
Then from the right side pane, click on Enter Product Key

As you can see, I have the Mailbox and the Client Access roles installed on this server. Its version number is 15.0 ( build 5126.32 ) and it is Standard trial Edition and currently unlicensed.

So to activate it, click on Enter Product Key
Enter the product key and then click save.

After you enter the product key, you must restart the Microsoft Exchange Information Store service so that the change is applied. Depending on the product key that you enter, Exchange will determine if the server is running the Standard Edition or Enterprise Edition of Exchange 2013 and update any necessary settings.

After you click ok, you will be back to the servers page, with a note on the right side pane reminding you that the changes won't take affect until the Information Store service has been restarted.

To restart the Microsoft Exchange Information Store service

Open services.msc
In the Services Management Console, find the Microsoft Exchange Information Store service. Right-click the service, and then click Restart
After the service is restarted, logon again into EAC and check the status of the Exchange Server. You will notice that the changes are applied and now you have a licensed Exchange Server 2013.