That ‘Authentic Stan Lee Excelsior Approved’ sticker comes from Stan Lee directly. At comic book conventions, usually people who waited in line and purchased his signature would get a similar sticker (only difference is they would receive a sticker with a special number that correlates to the COA paper they would also receive). I believe these were available through his website. As for the signature itself, I believe the above Stan Lee signature is Genuine. It’s Stan’s later signing style where his ‘L’s are looped instead of a hard ‘L’ shape.