Does Apple allows restricting In-App Purchase DLC Non-Consumable Content to one device? I have been reading the review guideline: https://developer.apple.com/app-store/review/guidelines/

I see section about for subscription its has to be available for all iOS devices of a single user:

Content subscriptions using IAP must last a minimum of 7 days and be available to the user from all of their iOS devices.

But does that apply to Non-Consumable Content as well?
I am worry Apple will reject our app because of this reason.
You are afraid Apple will reject your app because you use non-consumable content on only one device? 

One of my project has in-app purchases only for 1 device. The app is already 6 years continuously reviewed and successfully deployed. Believe me, this is not an issue aslong you are not using a subscription. 

The only problem you are facing is someone can buy the DLC also on a other device and it will auto unlock as it has already been purchased with the same Apple ID. There are ways to prevent this by securing your app via a database.