I've read you need to train yourself to keep a plug in for that long. Start with 20 mins, then 40 mins, etc. You need tobuild your tolerance. Carry lube for when you need to relube(maybe try silicone lube, but thats for non-silicone toys). Also carry plastic bag incase it needs to come out.

Some butt plugs are simply not designed for long periods of usage at a time. The ones that fall into this category typically fall out rather easily. The best kind of plug to use for this purpose is one that has a relatively wide flared end and long neck along with a nice sturdy base. These tend to stay in for longer durations.
Secondly, yes, you do run the risk of the lube drying out before you take it out. This is best remedied by finding a lube that is known to stay wet for lengthy periods of time. Try a good silicone lube(as long as the plug is silicone compatible) or even some water-based lubes can do the trick. Attempting to pull out a plug after the lube has dried is obviously VERY painful. The best recommendation I can make is for you to buy a specialized lube syringe; these allow you to sufficiently lubricate the inside of the rectum to help ensure it doesn't dry out. If it does dry out even after using the syringe before insertion, you should still be able to fit the syringe into your anus with the plug still inside. Easily guide the syringe into your anus and squirt the lube all around the sides of the plug. If you can't find a lube syringe and if you're willing to spend $20 for a only a few shots of lube, then you could try purchasing the Astroglide lube shooters. They contain a small amount of lube in a prepared one-time-use shooter. You can find these in the EF store. Unfortunately, EF doesn't sell any of the lube syringes, but you should be able to find one at your local sex shop.