LMT Karte: time limits

What are the applicable time limits when I purchase or use an LMT Karte?

What is the balance expiry date of my LMT Karte?

What is the use-by date of my LMT Karte?

What is the validity period of my LMT Karte?

What happens if an LMT Karte is refilled with a lower denomination renewal card followed by a higher denomination card?

What happens if my LMT Karte is not refilled by the use-by date?

How accurate are the time limits of my LMT Karte?