There are a finite number of lifetime licenses available, so redemption of these licenses is restricted to 1 per class C per 12 hours to prevent monopolization. You may always upgrade from a trial license in the panel. Just wait for the cooldown window to expire.
As for RHEL8/CentOS 8, waiting on third-party repos to catch up with their distributions (e.g. Ansible is missing from EPEL). I only build from source when it’s absolutely necessary to avoid crossing over domains. It’s a hosting platform, not an RPM repository so it’s better to leave that aspect to the experts. I’d like to get moving on it by the end of the year, but at the same time would like to avoid being a guinea pig for upstream package compatibility.
You may always migrate an apnscp account from one server to another using the built-in migration facility. It’s what I’ve used over the last 15 years to move customers from platform to platform as they’re released.