[Kanbab]

Can you consider saving users data via cookies or ip? That way the next time they come back their stuff is still there. Now on the second run and beyond, you can remind them that they can take their data with them to other computers, or privately, if they create a login.

[xSwag]

Some people might have dynamic ip addresses. Cookies can expire and get purged very easily. Same with local storage.

[amikazmi]

Also, people use many machines (desktop, laptop, tablets)