There should be no records kept of transaction after a completed delivery.
Order History should be deleted afterwards!That's what I think of the situation anyway.
While keeping records on your online system is different to keeping them in a standalone server or such, generally recoprds need to be kept for tax purposes, for many years.
Not to mention, if they don't keep records, and you are not satisfied with your product and wish to return it, they would no longer have a record of your transaction meaning they won't be able to refund you.
Businesses keep records for a reason. But as i say, it doesn't have to be connected to the online site. This as suggested by EM, is an issue with the site developers, not the shop.
No online shop deletes it's order history if you hold an account there, not for many years. They are not doing anything illegal in selling cannabis seeds, and as such they operate like any other shop, which is specifically why seedbanks state that you must check your local laws before ordering seeds. They are uk based, so there is absolutely no reason for them to delete transactions and order history, everything sell is 100% legal.