Working for an insurance company

Firstly: 

Life insurance is a kind of commercial insurance, which is haram, because it involves uncertainty, riba and gambling, and consuming wealth unlawfully. It is not permissible to work in commercial insurance companies, because this is a kind of cooperating in sin, which Allah has forbidden, as He says (interpretation of the meaning): 

“Help you one another in Al-Birr and At-Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allah. Verily, Allah is Severe in punishment” [al-Maa’idah 5:2]

See also question no. 8889. 

Secondly: 

There is nothing wrong with your keeping the money that you earned from working in that company before you came to know that it is haram, because Allah says (interpretation of the meaning): 

“So whosoever receives an admonition from his Lord and stops eating Ribaa, shall not be punished for the past; his case is for Allah (to judge)” [al-Baqarah 2:275]

With regard to the money that you took from the company after you came to know that it is haram, then you have to get rid of it, because it is haram wealth, so you can spend it on charitable causes. 

See also questions no. 33852 and 2492. 

See Fatawa al-Lajnah al-Daa’imah li’l-Buhooth al-‘Ilmiyyah wa’l-Ifta’, 15/8. 

And Allah knows best.