I still have the OEM shower curtain installed in my eleven year old rig.
Generally I let the plastic dry off and stow it with the strap between uses and when moving. This keeps the pleats from stretching and flattening out.
The latch started having problems catching a couple years ago and recently it stopped altogether. I found that the screw holding the catch to the shower frame was only long enough to go through the plastic of the frame and was very loose. I got a longer screw that bites in to the wood frame behind the plastic shower frame. The head of the screw is a fraction of a millimeter larger than the latch so it also helps to hold the door latched. Now the door/curtain stays closed during use.
If properly maintained and cleaned your curtain should last a long time.