Autosave (friend forgot to save)

Recently I gave a poll to my friends about a meeting and one of them did not notice the "continue" button on the bottom (on phone) so his response was not saved. Then, we were angry at him that he did not fill the poll and he was angry that I use a stupid website which did not save his responses.

In general, I think it is easy for people to miss a "save" button if they are in hurry and tired after checking their calendar several times to fill a long poll. So a workflow where the user can leave the page at any time and not lose their responses would be better, in my opinion, and it would avoid many unpleasant scenarios.