We recently upgraded one of our RedHat-5 server to RedHat-7. I ran the subscription-manager to register the system, but it complains that there are no subscriptions available to assign.
I checked my subscription inventory in customer portal, and there is 1 available. I removed the old system.

Do we need to buy new subscriptions for RedHat 7? Our license document doesn't list the RedHat OS version anywhere, so i assumed that the same license that applies to 5 also applies to 7, as long as its valid (we recently renewed it).