I have PDFpen 8.2 and later. How can I restore PDFpen Library items?

Beginning with PDFpen/Pro 8.2, the PDFpen Library is able to sync with iCloud. If you are signed into iCloud please make sure you are signed in with the same name on devices you are syncing with. If you are having trouble with the Library you can turn off iCloud in System Preferences by going to iCloud > iCloud Drive > Options and unchecking the box next to PDFpen/Pro. Otherwise, the library items will automatically be uploaded to iCloud. If you turn iCloud back on, the imprints should reappear in your library.

If you previously synced with iCloud, but are having problems with a new Mac (or for any other reason), try: 

System Preferences -> iCloud -> iCloud Drive -> Options and uncheck the box next to 'Optimize Mac Storage'

Meantime, here are the instructions for an easy way to manually back up and migrate your library:

1. Launch PDFpen
2. File -> New One Page Document
3. Bring up the library and place each of your signatures on the page.
4. File -> Save
5. Close PDFpen and open PDFpenPro and open the document you just saved.
6. Bring up the Library.
7. tools -> Edit tool (if it's not already selected). Click on a signature, then click on the + on the library box and choose 'Add selected imprint'. You can repeat this for each signature.

If you are still having troubles or did not have iCloud enabled, please see How can I restore PDFpen Library items?