Minimum 25% of each share should be payed when the company is established

The remainder of the capital will have to be payed whenever the management of the company decides that the company needs it. Asking the payment of the remainder of the capital to the founders is the responsability of the management of the company.

(Source: artikel 448 Company Code)

The founders are responsible for the full sum of the capital. If the company needs the money, they will have to pay it, regerdless the limited responsability.