SiteBrains generated with version 126.96.36.199 do not require a license key and the license key error can only happen if you set an invalid key. By using an empty key, you should never get a license key error.
It sounds like you are dealing with a caching problem. The problem could be in IE - whose cache is notoriously difficult to clear - or even on your Web server.
I would recommend that you change the settings back (remove the license key) and then:
1. To check if the problem is your IE cache, try accessing it from a separate computer which has never accessed the page before. If it works, then you have local cache problem. If not, then it might be your Web server or maybe a proxy server on your local network.
2. To check if the problem is a Web server cache or proxy server cache, republish your Brain at a different location and try accessing it. If the problem goes away but it did not in step 1, then it's either a proxy cache or a Web server cache. You will need to consult your Web server's documentation for information on how to clear its cache.