Allow participants to change their votes up to the deadline date

Hi, I have just joined the premium account. I'd like to setup a photo poll where participants can change their votes up to the deadline date or when the poll is closed. What's the best way to do this (if it is possible)? I'd like it to be as secure as possible but by sharing a link it means they can't go back and change their scores once the link as been used. Many thanks.

Hi David,
Thank you for the purchase!
Users can change their votes until the voting is closed.
If you invite users with an anonymous link, they are still able to change their votes, but they cannot participate as a different user (e.g. vote for an image twice or more).
Kind regards
Philipp