Will a person be held accountable for buying and raising a dog at home without knowing that it is forbidden, and what should they do after learning the religious ruling, especially if a long time has passed since acquiring it?

It is forbidden to own or raise dogs except out of necessity, as the Prophet, peace and blessings be upon him, said: "Whoever keeps a dog, except a dog for herding livestock or a hunting dog, will have two Qirats deducted from his reward each day." If the dog is not of a type permitted to be kept, then it must be removed from the house, and it is not permissible to sell it. If you bought it unaware of the ruling, there is no sin upon you.