Your clipboard (or pasteboard) can be found under the "Import" button on canvas. Tap "Import" to open the menu, and find the clipboard icon.
 
You can use the clipboard to copy strokes or images in a drawing, between drawings, or between apps.
 
To add strokes to your clipboard:
  1. Select the strokes you want to copy.
  2. Tap the paperclip icon in the Selection popup or tap the clipboard icon under the Import button.
You can also copy images (photos or colors) to your device's clipboard, for example, from the web or Photos.
 
To add a stroke or image from your clipboard to canvas:
  1. Tap on the canvas (outside your selection box if active) and a clipboard icon will appear.
  2. Tap the clipboard icon and the copied item will paste to your canvas.
  3. Alternatively, you can tap the Import menu and choose "Paste from Clipboard".