Rendle, the Drudger Repair Vendor who got rich off our exploits in Castle Nathria, has popped up in Haven.
He is selling every Legendary Memory that was only obtainable in Castle Nathria for 2500 Cataloged Research, 1500 Cosmic Flux, or 400 Soul Cinders.
So if you have switched mains, or simply never progressed thru Castle Nathria, you now have another way to obtain those memories very easily.
He is located right behind the Haven Enlightened Quartermaster.
Hope this helps,