Hello marvellousmushro,
Thanks for your post and welcome to the QuickBooks Online Community.
QuickBooks looks after your data and we'll automatically back this up for you, and give you access to your account for 365 days from the date of cancellation so you can export any data needed.
While we don't provide physical copies of the backups, there are other third party sources who can do this for you, to allow you to re-store to previous points, if this is what you are requiring.
Thanks