HI,
Premium developers can apply for a CloudStore key, which is used like this
cld = app.CreateCloudStore(
apiKey )
(normally CloudStore is then used to store data like high-scores in a game, that are common to everyone).
You could try storing data for individual users by using their email address as filename (possibly substituting dots and @ signs)
but all the users combined would be included in the CloudStore limitations for the key.
The alternative would be for each user to have a key (that you or the users would have to pay for).
Regards, ah