Thank for report the issue with the Sitefinity license key you downloaded. There was a temporary glitch in our system that is already resolved. You should be able to also manually activate Sitefinity license keys downloaded from you account now. I have updated your account with 500 Telerik Points.
Please, note that in your account on the Sitefinity License Management page the Download license key link downloads the license file for the latest official Sitefinity release. If you would like to download a license key for an older Sitefinity version such as version 3.7 you need to click on Manage for the particular license. The Manage link will take you to page where can manage the individual license, see its license subscription utility meter, and download license keys for older Sitefinity versions.
In regards to your question, Sitefinity displays a trial message under your development domain because this domain is not licensed. Your licensed domain is travelinsured.com. There is no problem to continue your development under the domain http://devweb, but you will continue receiving a trial message every few clicks. On the hand, you can use a sub domain such as devweb.travelinsured.com to access your development environment. In this case, Sitefinity won't throw a trial message because you are accessing the project through a licensed root domain name.
Don't hesitate to contact us, if you have further questions. Good luck with your project! We wish you a successful website launch on Sitefinity 4.0!