Microsoft introduced Activation with Office 2011. Since Office 2011 was first released, Office365 subscription service was added. The retail copy of Office for Mac and the Office365 Subscription service use different activation processes. The number of installs also differs. The retail version will depend on what version you purchased (one or two computer install, or family pack that installs on 3 computers). more info. The Office365 Subscription service will install on 5 computers more info.
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Continue Reading: Microsoft Office Activation FAQs