Windows activation in DR

We have our production Windows 7 view machines activated thru a KMS server. We have a DR environment also. We took the master image (which was KMS activated) that was in production and copied it to DR and were able to spin up machines in DR after making the SkipLicenseActivation regsitry change. The machines that were spun up are now showing that their license will expire soon, since they don't have access to the production KMS server.

What is the best way to handle windows activations in a DR segment? Use MAK keys?

Thanks