After purchasing the app from
Gumroad, head over to the Chrome Webstore and install UnderlineMe.
On startup, it will ask you for your license key. Use the one
you have got in your Gumroad email.
That's all to it. Click on the extension icon in your
browser's toolbar and start taking notes.
Right click on the extension icon and click on 'All Notes'.
This will take you to your dashboard from where you can browse
Not yet. Sync will be coming in a future update and it will be
billed on a monthly basis.
Ability to highlight PDFs is coming in a mid-august update.