well, here's the rule on the 5 installs:
Office on 5 PCs or Macs plus five iPads or Windows tablets
and here's the recent information on Surface Pro 2 as a tablet (
Office 365 users: Surface Pros now qualify as PCs or tablets | ZDNet):
Microsoft officials had said previously that Surface devices, because of their detachable keyboards, counted as tablets, not PCs. While Microsoft officials often refer to Surface Pros as "tablets that can replace your laptop," they also position them as competitors to MacBooks, not iPads.
When Microsoft unveiled Office 365 Personal in March, Office execs said that "Any Windows device that is touch enabled and has a detachable keyboard qualifies as a tablet." That meant Surface Pros and Surface Pro 2s were defined for licensing purposes as tablets.
But more than a few Surface buyers are using their Surface Pro or Surface Pro 2 devices as their primary PCs. Some considering Office 365 wanted the option to count their Surface Pro as their PC and Office on iPad as their "tablet."
The good news: Microsoft is now allowing users to do this. When I asked Microsoft officials about their categorization of Surface Pros for subscriptions, a spokesperson sent me the following statement:
?We understand that the convergence of device categories can make it difficult to define some devices, and as a result, we have built in some flexibility for subscription customers. For example, an Office 365 Personal subscriber can define their Surface Pro as either a PC or a tablet.?