Renew License

Running Win 7 x64 I’m unable to renew the license of the software. Once the Renew button is clicked the windows disappears but continues to run in the background. Unity is running in the background holding on to 25% of CPU and growing RAM usage however, nothing more occurs. Uninstalling and re-installing Unity with a fresh download has not helped.

I had a similiar problem: I can't downgrade from the Pro trial after it expires? - Questions & Answers - Unity Discussions

My solution was to uninstall, use regedit to find all related license keys (especially those that are part of Unity’s anti-piracy suite), delete them, and delete other system folders. Then it worked.