On Amazon I buy the book DL it to my PC transfer to Calibre, Remove DRM Transfer them to my External HD. Then use Calibre to Side load them into the Readers. Then Dleete the books off my Amazon account. Exception is I keep on Amazon ALL the ebooks with Audible companions so I can use the Immersive Reading feature. Reason I have Over 1400 ebooks but only 300 on my account

Then I have to be careful not to duplicate those 300 ebooks! when side loading into new ereaders. Which is why I get so annoyed when the ereaders are not working correctly