You only have to start Pageant once (per Windows login) to make it available for all apps including SourceTree - what I tend to do is add Pageant to my Startup folder in Windows and give it a parameter of the .ppk key, that way when I log in I have to type the passphrase and then it's available for all apps.
However alternatively if you set the key in Tools > Options > SSH Client inside SourceTree and check the box 'Automatically Start SSH Agent' then if Pageant isn't already running when SourceTree starts, it will start it for you and load this key. You will still need to type the passphrase, this is a security measure which is safeguarding your key from other people should they somehow get hold of it.
Supported Platforms macOS Windows We recently introduced support for additional hosting services such as GitHub Enterprise, GitLab (Cloud, Community Edition, Enterprise Edition), and...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs