Actually, it might be the end of the project. Yesterday I had legal counseling and the conclusion was that it is difficult to protect myself against legal trouble resulting from people misusing the service for illegal and/or criminal purposes. Blocking not allowed traffic is already difficult for big companies, so that is not a feasible option and then I am not even speaking about the privacy-related consequences. The problem is that even when I am completely innocent, defending myself against claims costs serious money. If you need examples, search for what happened to some people running a TOR exit node.
As a result, I am considering to remove VPN/Sentry from the Play store (this seems to be the only way to stop renewing of existing subscriptions as well) and to keep it for private use only. Maybe I will try to sell the product to one of the big VPN providers.