I have thought about the best term for the opposite of "openly-licensed" resources. Remember that no one "owns" creative works. They belong to all of us. Society grants a monopoly to creators with a "copy right" for a limited time. Creators own the "copyright" NOT the resource. (Or they can sell their copyright). This monopoly is a privilege that was extended to creators with the first copyright laws in the 18th century.

But how do we  semantically distinguish  openly-licensed resources from non-openly-licensed resources?

"Intellectual property" or "IP" is an Orwellian term. Copyright is NOT a property right. It is a "privileged monopoly". IP is used however, to describe open resources as well as others, and so does not only refer to Britney Spear's songs but can also include the Creative Commons (CC)-licensed works of Nine-Inch Nails.  

I used to use "proprietary resources" but that is not correct, because under open licences, the author remains the "proprietor" and still owns the copyright. So opely-licenced resources are just as proprietary as others.

"Commercial resources" doesn't work either as some open licences allow for the commercial use of resources. And, by adding a "non-commercial " restriction to an open licence, that does not mean you cannot use a resource commercially. It only means that you cannot use it commercially without permission from the copyright owner.

"Closed resources" doesn't work either because many resources on the internet are freely available online and so not "closed". They can be accessed and used, but they may not be openly licensed.

"Owned resources" is not correct. Except for public domain resources, all resources are owned whether they are openly licensed or not.

"Restrictively-licensed resources" might be useful, but many would argue that  open resources with  CC restrictions such as "no-derivatives" or "non-commercial" would also be included under a "restrictively" licensed appelation.

"For-profit resources" does not cover a vast range of not-for-profit content that is not openly licensed. And, open content can be used for profit, especially when there are no added restrictions or with the permission of the copyright owner.

 "Unshared resources" is also not accurate. Although openly-licensed content is shared, that does not mean that other content is not shared. Many resources on the internet are shared, just by being on the internet, but they may not be openly-licensed.

"Monopoly-controlled" is a better description, as an open licence means that the creators forego the privileged monopoly that is granted to creators by the state. Openly-licensed content is not monopoly-controlled, although some could argue that when the owner puts restrictions on their copyright, such as no-derivatives or share-alike, that they are exercising at least limited monopoly control. 

"Default licensed resources" is perhaps one of the most accurate terms because ALL content comes automatically under strict copyright protection unless the licence is modified by the copyright owners by adding a Creative Commons or other licence. Unfortunately, I suspect that people will not readily take to this term as an antonym for openly-licensed resources.

All the way from New Zealand, Wayne Mackintosh suggests "All rights reserved content", which is rather ugly, but perhaps the most accurate term. Many describe CC licences with "Some rights reserved" so there is a fit as a suitable antonym.

Or, perhaps, there is no real antonym just a sliding scale, with offshoots between the public domain and the strictest copyright enforcement.