Chris wrote:
There's no separate revoke step to worry about, and there's no account-page button — licenses are managed right in the dashboard. Going forward, on a box you're about to retire, open Settings → License and click Remove license; that frees that box's slot. For the boxes you already uninstalled, you're still fine: each key holds three concurrent activation slots, and a fresh activation automatically recycles the oldest one as long as you activate with the exact email you used at checkout. So just install and activate with that email. If it still shows only one and refuses, tell me and I'll flag it to Tom.