The license lets you install the version you purchased on the number of production domains included in your plan, plus a staging domain. You can move an activation between domains from the customer portal, within that limit.
The customer package includes only the public verification key. The vendor private signing key is not part of the package and is not stored on the installation.
The end of updates and support does not remove your right to use the installed version. Explicit revocation after a full refund stops new commercial actions on that installation once it accepts the license state, without deleting your files.