Bricky
Store in this context refers to a Retail site where you buy books and not a place to Keep BOOKS (STORAGE, WAREHOUSE...).
My advice is always get your purchase soonest, and control where YOU store Your Copy (probably with the DRM gone as that might also go
south at sometime)
Calibre is a great way to manage A Library (but as a brick & mortar , Library. The Librarian has set methods for a reason). Simple Libraries can usually get away with some file folders, but as it grows... being able to find books by Keywords or fragments of words is a + (

start now, doing catch-up is H3ll. I did the metadata only for my paperback collection in Calibre. About 1 YEAR of an hour+ a day working on it)