So I currently have a convict that has mated before when I bought it at my lfs 2 weeks ago and am wondering if I were to Introduce a female in there, then will they for a pair or is it impossible since I heard that they are monogamous.
Convicts are one of the most prolific breeding cichlids in the hobby. I don't believe monogamy is part of a convict's lifestyle, although like with any fish there are exceptions. It wouldn't be unusual for a male Convict to kill its mate.
If your tank is large enough, consider adding two or three female Convicts and allow a more natural pairing.
On a side note, It's difficult to find a fish store or another fish
keeper that will take an unwanted Convict.