So, I'm still fairly new to Macs. I have a legit copy of MS Office 2011, 25 letter Office Key that I have used twice, once to install on a 13" rMBP that was later returned and then to install on my current 15" rMBP. I am going to do a clean install of Yosemite today and have a little concern. So, I couldn't find my dmg of office installer, tried to get it from the MS Office download site. It told me the product key was not valid when I tried here: https://downloadoffice2010.microsoft.com/macdl/registerkey.aspx?culture=en-US&ref=macdl So, I found a dmg online. My valid product key isn't being recognized here either https://officeformac.getmicrosoftkey.com or here: https://downloadoffice.getmicrosoftkey.com Should I have released the license on the first 13" before I formatted and returned it, and should I do that again before I upgrade to Yosemite? Now that it has been activated twice but only used one at time and the first one has been discontinued since the second one was activated, am I going to have buy a product key again?