Originally Posted by mixerdlb
My wife and I share a Nook eBook reader (Barnes & Noble) and have purchased numerous books for it. I also had books that I purchased from another online site. The Nook For Android app claimed that it would sync to the furthest page read on both devices, but what I found was that it would only sync books purchased from Barnes and Noble. I called Amazon and asked if their books had the same restrictions and was told they did not. I ordered a Kindle, installed the Kindle for Andoid app and converted my Nook books (epub) to Kindle format (azw/mobi). Guess what? None of the books will sync in either direction. I now have to write down the location number of the page I stopped at and enter it in the other device to get it to sync. I think I'll return it and just read on my Droid.
Don't return it just yet!
I had an eBook on my phone that was on location 47 or something. I hit 'menu', 'more' and then 'Sync' and it offered to take me to the furthest page read on any of my devices (7000, in this case).
I know I've seen the same option on the kindle it's self too
(Obviously, make sure you have an internet connection when you're reading, otherwise it won't be able to tell the Amazon servers where you left off).
EDIT: I should add, I don't see this working with any of your converted books. But then that's to be expected.