Sorry, your license key isn't valid for this domain when using virtual hosts

Hi, I always develop in a subfolder which leads to a multitude of issues when going live. So I've set up a virtual host which I'm hoping will avoid the same issues. I've installed Perch as usual, but haven't bought the license yet. When trying to login to Perch I'm getting the message:

"Sorry, your license key isn't valid for this domain. This license key is for local testing only, so can only be used on a non-public domain." It's a local site and not accessible on the web. The URL is "dev.companyname" which is the virtual host for localhost/companyname/

Any ideas?