Dafni;
Most manufactures say 500 cycles if treated gently. I expect to see 200 out of my packs (I charge at 2c and discharge to the lowest possible voltage 2.7 volts per cell). You will see a perfomace drop in cells after 50 cycles and then they typically decrease in performance (a little at a time) till they are no good.

A good rule of thumb to use when using and purchaseing lipos is "80% on all ratings"
So lets say you have an application on a car that requires 50 amps, you need to buy batteries that can handle 20% more than 50 amps. That would put your average use at 80% capacity with the ability to handle larger bursts from time to time. DO NOT USE THEM LIKE NIMH or NICD to limit the current to an paticular application they will get VERY hot and possibly vent with flames if they cannot handle the load.

Also lower voltage cut offs is VERY bad for lipos. Stay around 3.0 volts per cell when dischargeing.
Hope that helps