Licencing DR Server

I want to build a test Disaster Recovery BE server to connect to our replicated Data Domain store and run an inventory and do some test restores from it.

Can I do this without a licence? We don't need to run BE at the remote site other than in a DR situation, but simply want to test our setup. The test server will either be in cold storage until a DR situation or we'll blow it away again depending on the options.

Or is it the case that I need CASO and an additional licence to do this properly or by best practice?

Thanks in advance for any info.