Why would someone need alimony? Alimony has many connotations, but the primary reason for someone to seek alimony after a divorce is that he/she cannot maintain his/her current lifestyle without the financial assistance of the former spouse.
Whether you or your spouse stayed at home for the kids with no prospect of employment, or you both have been financially dependent on each other during your marriage, alimony might be an option.
Can you ever stop paying alimony? Unless another agreement is arranged, alimony will end after the maintained spouse remarries.