Office 2013 product key - how to I locate it?

If the install was via Subscription, you do not need a key to install, just an email address.

If Volume License or like, you (or someone in the organization) should have an email with the key. You may have to contact Microsoft Support for this.

You could download software like magicejellybean and it can get the key for you.
However the previous poster is also correct in their statement.

Try http://www.belarc.com/products_belarc_advisor. Codes for most software on the computer will be listed in a web page format.

If using the perpetually-licensed/boxed versions, Magic Jelly Bean, Produkey, and Belarc probably will not pull the key. It will for 2010 and probably for VL/OL licenses, but not for perpetuals.

Use the following to find out the last 5 characters of your installed key, to match up with the install listed in office.com:

https://technet.microsoft.com/en-us/library/ee624350.aspx

For example, for Office 2016, run: cscript "C:\Program Files\Microsoft Office\Office16\OSPP.VBS" /dstatus

However, John is right: unless you can get into the Office account it is associated with, you won't be able to activate it.

I also recommend produkey--it will find all Microsoft keys on your system, Windows as well as Office (as well as many others see link for further description) http://www.nirsoft.net/utils/product_cd_key_viewer.html

which of the solutions provided helped you--please respond and close the question with the solution that helped you--thank you

Thanks