I fish a private lake that the game commission encourages us to keep fish under 13''. Weds evening I get one with eggs inside of it. We are still a little ways out in my neck of the woods for the fish being on the beds, especially the smaller females. And I'm curious as to how long eggs are present in a LMB. This would be under good conditions with the weather's cooperation.

Much of the year. Ovaries begin to develop in the fall (up north here) and there can be eggs left over into early summer.

Good question.  I could try to answer it, but would probably miff it, so watch this video of one of the country's top warm water biologists instead.  He talks about this in the video:

http://www.bassresource.com/bass-fishing-videos/bass-fishing-fish-biology.html

thanks glen!