If you have Wifi connection on your laptop you can do it like this, because it's free:
- connect your desktop and laptop with a lan cable.
- start up your laptop and desktop
- go to connection settings on your laptop, then to adapter settings.
- select wifi adapter + lan adapter and click on the right mouse button.
- click on bridge connections
This should work, the only drawback is that you have to turn on both computers and that the internet is a bit slower.