Google Photos Live Albums has a 10,000-photo limit13
There's one tiny thing that we didn't know about Live Albums though, which might be disappointing for photographers. It appears that you can only add up to 10,000 photos or videos to a private album. When the 10,000-photo limit is reached, you'll get a “Live album paused” warning, so in order to add new photos, you will have to remove some from your library.
It's probably not a big deal for ordinary users who take a photo or two from time to time, but for those who capture anything while on the move this might pose a problem. Another issue is the fact that Google Photos doesn't automatically delete uninspired or blurry photos, so you'll have to go through your library once in a while and manually removed them.
It's worth noting that a shared album has a 20,000-item limit, which means that two people can each add up to 10,000 photos or videos. Google also says that some feature may not be available when you have a large album, but doesn't mention what exactly won't work.