Hmmm… I’m confused… You should only receive 1 email with your license key. Are you perhaps referring to the PayPal confirmation which would include a transaction ID (not a license key since it is PayPal’s record of transition).
Any way to enter you license key, navigate to the Connections : Settings admin page and click the Licenses tab as you did initially. Copy/paste your license key into the field for cMap and click the activate button. That should be all.
Hope this helps, let me know.