Is it modifiable?

The divorce order gave my ex-husband the option to pay a monthly lump sum over a period of nine years or to accelerate the payments without penalty. The order states that this monthly lump sum will be necessary to pay the mortgage, taxes, homeowners and maintenance on the house. Is this considered a maintenance order or something else? If it is maintenance or alimony, would it be modifiable if I decided to co-habitate or remarry? What are the factors that determine whether two people are cohabiting or not? Thanks so much for taking the time to read and answer my questions!