We have a similar system on our site, where users can bookmark pages to a planner/wishlist function. The saved items are sent via a webservice and stored on our server, and there is a corresponding get webservice.
We have a ‘lazy register’ system. The first time a user saves an item, they are asked for their email (but no password, as nothing is confidential). This is hashed and saved locally using a cookie, then used to set/get the saved items. When the user uses a different computer they are again asked for their email.
The key is that a register and a login are the same operation, so there is no need for any password reminders or any reset functionality.
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solved Remote alternative to local storage for low-security user data?