verify subscriptions to a Red Hat system

the process to attach/verify subscriptions to a Red Hat system. These are the steps to follow:

• SSH / Get console of the shell of the desired Red Hat system you want to subscribe with the subscription
• run subscription-manager register command and subscription-manager attach --pool=<POOL_ID>, the pool id can be found using subscription-manager list --available, this pool-ID is the unique ID respective to your subscription
• Internet connectivity to the system is required as the system will get authentication of the subscription from access.redhat.com
• verify the subscription is current/invalid from subscription-manager status command, If the output says  " Current " means the system is registered with proper subscription, anything other than this will come as an output saying "Invalid "
• The subscription can be attached to any Red Hat system, where the environment is started from RHEL 5.7 to the latest (7.5) one
• If the system had any previously attached subscription, please run these two commands one-by-one subscription-manager clean ; subscription-manager refresh at the system to clear out the previous metadata
• If the system had any previously added repository manually (not through Red Hat subscription) please run these command rm -fr /etc/yum.repos.d/* to delete any Repository configuration file which're not attached through a valid Red Hat subscription.
• You can also see the system attached to the subscription from your purchase account at access.redhat.com where the subscription will be shown attached to which system, the Hostname/ UUID.