If you make sure that your house or car or even a database stays in good working condition, you are keeping up on the maintenance.
Maintain, the verb related to the noun maintenance, comes from the Latin expression manu tenere meaning literally "hold in the hand," a fitting picture for this word. As well as the upkeep of machines, maintenance can be used with things that need sustaining. The maintenance of law and order is taken care of by the police. When a couple divorces, the husband is usually required to pay maintenance — financial support — to the wife.