With a prepaid card, it is not possible to set a usage limit. Of course, you can never use up more than the calling credit on your SIM card.
Do you have a subscription? If so, the standard limit is € 50 euro out of bundle. As soon as your out-of-bundle costs reach € 50, outgoing traffic from your SIM card will be blocked (calling, texting, and surfing). This ensures you won’t have any nasty surprises. If you want to, you can set your limit for out-of-bundle usage to € 0, € 25, € 50, € 75, € 100, or higher. To do so, please contact the JIM Mobile helpdesk via email firstname.lastname@example.org or on the free number 1984.