All pointe shoes have a limited life. Even Gaynor Mindens will eventually die! As for conventional pointe shoes, they can have a very limited life indeed - for professionals, it can be as short as one performance. However, there are ways to make your pointe shoes last longer.
Moisture - especially sweat - is what kills your pointes! Keeping them dry can make a huge difference to how long they last.
Never wear your pointe shoes on bare feet, because the oils and sweat from your foot have nowhere to go but into your shoe.
For class, fine cotton socks will absorb sweat better than nylon tights.
If you sweat a lot, spray your feet with anti-perspirant before class.
Don't keep your pointe shoes in a closed bag between wears - an open-mesh bag is better.
Never leave your padding inside your shoes.
When you get home from class, take your pointe shoes out and let them air dry thoroughly
If you're dancing several times a week, buy a second pair, so one pair can be drying while you're wearing the other pair.
Have you noticed those little packets inside vitamin bottles - the ones that say "do not eat"? You sometimes get them in the box when you buy shoes, or in packets of tortillas. They're dessicant - they absorb moisture. Save them up and put a few inside your pointe shoes when you take them off, and they'll dry out much faster.
If your box or platform has gone soft, you can get some more life out of them by adding a little Jet Glue inside the box. Be careful - don't use too much, and keep the shoe upright until it dries.