From the Screenhero home page:
If you currently use Screenhero, you’ll need to migrate your team to Slack before December 1st, 2017. At that point, the stand-alone Screenhero app will no longer work — but you can enjoy the same features in Slack.
The goal of Slack’s acquisition of Screenhero was to integrate it seamlessly into Slack. We’re just 5 weeks out from that being fully realized.