We value Open Source and make a point to release all our plugins on GitHub under a BSD License.
Download the WakaTime.py file from GitHub.
Inside Blender, go to File → User Preferences → Add-ons, then click the Install from File… button.
Install from File…
Select the WakaTime.py file.
Check the box to enable the plugin, then click the Save User Settings button.
Save User Settings
Hit the Space key to open the floating menu and type waka then click WakaTime API Key
WakaTime API Key
Enter your API key
then click OK.
Type some code, then visit your WakaTime Dashboard to see your stats!