For the most part, almost all the cards are temporary. Those that are permanent will say so on the card and in most cases you will get a marker to remind you.
The only one card we have had a real issue with so far is the "Shackled to a Corpse" card. That overall effect is permanent but can be cancelled for the current game turn by Germany spending a PP to do so (represented by Germany placing a 1 PP Tranfer marker on the Shackled marker) or in those areas that contain a German army with the A-H armies. It cannot be cancelled for the entire game in any case.