When you go from a premium user to a free user, all your existing flipbooks remain premium for a grace period of 21 days, but they will never be removed from your account.
After the 21-days grace period, the embeded flipbooks will get watermarked and only the first 30 pages will be displayed. Also, the flipbooks published as Unlisted, Password protected or the ones Shared with specific people will become Public (displayed on your profile and indexed by search engines).
If during the grace period or at any time in the future you decide to repurchase a premium subscription, your account will become fully premium again.
Important: Your flipbooks remain premium for 21 days but your account will get free user limitations, and you cannot create a new flipbook if you have more than 3; also you won’t be able to create new content over your existing flipbooks by using the premium features in the Editor.
Mention: The downloaded HTML5 catalog for offline use or self hosting, will never get the free user limitations if you have it saved on your computer.