Anyone who wants to see how convoluted Microsoft licensing can be should check out the company's Licensing How To blog, where officials answer questions from customers and explain policies, concepts and how to apply usage rules in specific scenarios.
For example, an October entry addressed confusion over whether and how Office 365 users can also access servers running on premises. The problem here is that, technically, end users need to have Client Access Licenses (CALs) to hit on-premises servers, but CALs aren't included with Office 365, which instead comes with User Subscription Licenses (USLs).
So how does this work? "The short answer is, it depends," reads the post, which goes on to explain that Office 365 users can access on-premises servers that are "equivalent" to the cloud servers they're licensed to tap. To map the equivalent Exchange, Lync and SharePoint on-premises and cloud products, the post includes a table with about 45 bullet items.
The post also ends with a list of caveats, such as that a CAL variant called a CAL Suite Bridge may be required for accessing other servers, such as Windows Server, which aren't included in Office 365 USLs, and that some Office 365 plans, like the Small-Midsize Business and Kiosk Plans, don't give users rights to access Microsoft on-premises servers.
A post from August dives into the significant licensing differences between SharePoint 2010 and SharePoint 2013, but starts with definitions for terms like Intranet, Extranet, Internet, Internal Users and External Users, as understood in the specific context of this on-premises collaboration server. The post also reminds customers that its explanations apply only to SharePoint and that "any underlying products, such as Windows Server and SQL Server need to be licensed based on their respective licensing models."
In September, readers of the blog were reminded that Microsoft publishes on a quarterly basis its Product Use Rights (PUR) guide "because the use rights and licensing terms change" and it's important for customers to be aware of these changes.
However, it's also important to remain aware of previous editions of the guide, because those "old" rights can continue to apply based on when a customer bought a particular product, according to that post.
The post also explains what applies in a "downgrade" situation. "In some cases, customers buy a licence through a Volume License programme for current versions of products with the specific intent on downgrading to a prior version of that product. When this is the case, you must use the PUR in effect on the Agreement/Enrollment start date for the version you licensed - not the version you will downgrade to and deploy or run," reads the post.
So if you buy a licence for SQL Server 2012 but deploy SQL Server 2008 instead, the PUR that applies is the one for the newer version of the product. Microsoft keeps a 10-year archive of the PUR guides on its website.
"As in the case with most all licensing related topics, there may be exceptions for certain products or Volume Licensing programs," the post warns.