Copyright on documents does not expire. You are the sole copyright holder of all documents you have created, and you are the only one that has the right to distribute your work. Users on Stuvia are only allowed to upload documents that they have created, and are the copyright holder of that document.
In case you have any questions about plagiarism or copyright, contact us via email at firstname.lastname@example.org or sent a message to the live chat.
For more information on copyright or plagiarism, see our Copyright Center.