Actually you can save in LR. Go to Preferences/General/Catalogue Sttings and check 'automatically write to XMP' to do it without any effort, you can do it manually but as I let it be done automatically, I cannot remember shortcut.
Most Importantly - This means even if you lose your LR Catalogue for some reason, there is a little text file [.xmp] next to file with all the changes and tweaks noted.
You also need to do this if you want to use LR and Bridge along side each other, as otherwise Bridge cannot tell what changes you have made.
And I'm currently having LR catalogue corruption issues via a LR bug, so don't think it won't happen.