Red Hat provides free license for developers on RHEL. When You create account on redhat.com, You can download latest version of RHEL, and automatically generate license. After downloading and installing the ISO, You need to register Your license, to update and install packages.
# Register Your installation to Your redhat.com account
# It will ask for Your login and password
subscription-manager register
# Now, You need to attach Your license to this installation
# It will take a while..
subscription-manager attach
# Now You have fully registered Your installation, update packages
dnf update
And that's pretty much it. Learn, Teach and Have fun.