1. On your Windows 7 machine, navigate to the following folder:

   %AppData%\Microsoft\Sticky Notes

2. Save the StickyNotes.snt file found within to an external backup device.

3. On your Windows 10 machine, close all instances of Sticky Notes and open the following folder:

   %LocalAppData%\Packages\Microsoft.MicrosoftStickyNotes_8wekyb3d8bbwe\LocalState

4. Create a new subfolder named Legacy within that folder.

5. Inside the Legacy folder, restore your StickyNotes.snt file and rename it ThresholdNotes.snt.

6. When you start the Sticky Notes app, your legacy content will be imported automatically:

https://superuser.com/questions/1138030/how-do-i-import-microsoft-sticky-notes-from-windows-7-to-windows-10