Your clipboard (or pasteboard) can be found under the "Import" button on canvas. Tap "Import" once and the clipboard with the paperclip icon will be shown under the button.

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
    or drag the selection and drop it onto the clipboard icon.
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 clipboard
    or drag it from the clipboard button
    or tap+hold on any empty canvas and let go to see a clipboard icon appear. Tapping that icon will paste the the contents of the clipboard on to your canvas.
To clear the clipboard, tap+hold the paperclip under Import.