TubeAssist works differently from TubeToolbox. TubeToolbox runs on your computer. With TubeAssist, your campaigns run on our servers. This means that there is a higher ongoing cost to keep your campaigns running.
As a result, we are unable to offer lifetime accounts with TubeAssist. If we did, we'd eventually start losing money and be unable to keep the service going. So unfortunately, we can't support converting lifetime accounts from TubeToolbox to TubeAssist. If you have any other questions, please let us know.