Molieben (from Church Slavonic Mol'ba - prayer, supplication) is a short liturgical service usually centered on a particular need or occasion: the new year, a journey, an illness, an act of thanksgiving, etc. It may be addressed to Christ, the Mother of God, or to saints. Its general structure is that of Matins, and it can be served either by request of the faithful or by decision of the parish Priest.
The Church asks us to "pray without ceasing" - Prayer is the life of the Church and the life of each one of us, members of the Church. And because Christ came to redeem and to sanctify the totality of our life, no part of that life, no human need, no occasion is excluded from the Church's prayer. The Molieben, thus, is the extension of the Church's prayer, of Christ's redeeming grace to all aspects and realities of our life. "...knock and it will be opened to you." --we are called constantly to knock at the doors of God's mercy and our faith assures us that God hears us and is with us.