License for multiple domains My usual development process is to build the site locally, then upload on a staging subdomain for client reviews, going back and fourth between the two environments for updates, before deploying it on its live environment.

From what I understand you can use the one licence key on multiple environments but you can only then login to the Admin area from one of them? Which would cause me issue when I have the staging site up but I'm working between that and the dev version?

Alternatively I can use Craft for 'Free' using a appropriate .dev or staging URL (eg. http://staging-subdomain.mysite.com) and then make sure the paid for license is in place on the live version. Is that correct?
From what I understand you can use the one licence key on multiple
  environments but you can only then login to the Admin area from one of
  them?


Sort of – you'll be able to login everywhere, but if the license isn't valid the CP will be blocked behind a "upgrade-wall", prompting you to purchase a valid license or downgrading to Personal (the free edition). The frontend will continue to function as normal, though.


  Alternatively I can use Craft for 'Free' using a appropriate .dev or
  staging URL (eg. http://staging-subdomain.mysite.com) and then make
  sure the paid for license is in place on the live version. Is that
  correct?


Yes. From the docs:


  You’re allowed to run a single Craft license on multiple domains (e.g.
  example.com and example.fr), so long as they’re all a part of the same
  website. In order to enforce that, Craft does have one technical
  limitation: you may only access Craft’s control panel from one public
  domain per Craft license. (There is no such restriction on non-public
  domains, though.)


One of the ways Craft determines if the domain is non-public, is if the site has a dev-sounding sub domain (e.g. dev, local, stage, or staging). This means that a Client or Pro license registered to www.mysite.com should also work for a staging site at http://stage.mysite.com.