Yapps free for the PC as well. It is necessary to sign up but it was painless and did not got hit with any spam/publicity in the week since.
Tried it when it came as part of my last tablet and was under the impression that it was for free but alas no, after a month it was all a dream and subscription was required.
But I did ike it but was not ready for the subsription...
Now it is actually for free and if having a Samsung device with a pen it is even better!
For PC:
www.sketchbook.com/
Google Playstore:
play.google.com/store/apps/details?id=com.adsk.sketchbook