french sim card lasting more than 30 days?

Beverly, I find that a strange statement. I have never seen SIM cards with a time limit. Do you imagine the French have to buy a new SIM card every 30 days to put in their phones?
A SIM card will be either Pay-As-You-Go, in which case it lasts as long as you keep topping it up and using it; or you have a contract and you will get a bill at the end of each month. Pay-As-You-Go cards often have to be used at least once every 3, 6 or 9 months (it varies); after that they give the phone number to another customer. But I have never heard of one that has a fixed time limit.

Beverly,
Chris has given you great information.

I'm on France now & have yet to find a SIM card that allows international calls to the US @ a reasonable cost.

We went to the Orange store yesterday & I was given 2 choices for prepaid SIM cards; one would only allow 60 minutes for calls to the US in a 30 day period, the 2nd choice was €1 per minute for calls to the US.
Needless to say, I did not buy a SIM card & have been using FaceTime to call my family in the US.
All the hotels we've stayed at have free Wi-Fi, as well as many restaurants.

We use CelloMobile sim cards which never expire. With one inserted, your cell has a UK number. Using one takes some getting used to (we have to review the procedure yearly because we do foreign travel only about once a year) and the rates aren't particularly cheap, but having a card that never expires is worth the hassle.