If you are into drawing, sketching or want to learn more about it, this week AutoDesk is offering 50% off their normal $29 annual fee for the professional version of their desktop app. With your paid membership, you get access to pro features on both your iOS device and Mac. The promo code appears to be SKETCHSAVE50 although you may not need to use it to get the savings.
The Sketchbook Pro mobile app has been optimized for use with the iPadPro and Pencil. You can learn about the mobile app here.
Visit https://www.sketchbook.com to learn more about the advantages of membership for your desktop. You can always download the app and use the limited features for free.