From the documentation, the SDK has two licenses: GPL for non commercial use and a custom commercial license that may or not cost money.
There's a couple of issues here. First, this makes the PrioVR unable to be used for non commercial development with an Oculus Rift (the Oculus Rift SDK is not GPL compatible). So if I want to make a free demo that combines the Rift with a PrioVR I need to buy a commercial license?
Second, your non commercial use restriction appears to violate the GPL.
From the official GPL faq:
"I'd like to license my code under the GPL, but I'd also like to make it clear that it can't be used for military and/or commercial uses. Can I do this?
No, because those two goals contradict each other. The GNU GPL is designed specifically to prevent the addition of further restrictions. GPLv3 allows a very limited set of them, in section 7, but any other added restriction can be removed by the user."
Some more information on how the commercial license is decided to be free or not would be handy.
(It's not just oculus support. My engine framework also uses the free versions of Fmod and Havok, both of which are incompatible with your sdk in GPL form)
The use restrictions for GPL are not within the GPL license itself but in the super-license wrapper as to which license applies in that case, so there is not a conflict with GPL. The commercial license is free as long as it is used in support of YEI products.
Let us know if you have any more questions!