Hello Duncan.
Thanks for your question. I'm sorry to hear about that frustration. When working correctly the software should absolutely stay signed in. If you have already uninstalled, restarted your computer, and reinstalled the software but it keeps signing out then there may be a larger issue going on. Do you have any other filtering software on that computer? What kind of antivirus do you have installed? Are there any advanced protections or custom DNS being enforced on the router or ISP? All of those can potentially contribute to the sign out issue you seem to be experiencing. If you aren't sure of the answers to those questions or would like our more direct help I might recommend either chatting with us on the website or calling our Member Care Team directly at 989-720-8000. Otherwise I'm more than happy to assist you here on the forum.
Thank you and have a great day.