There are several reasons why it can be necessary to obtain a certificate from a country that you once lived in:
You may need to so in order to successfully complete a legal process, including taking-up employment that requires a clean criminal record certificate or perhaps a certificate of divorce in order to re-marry or a certificate of marriage which can be required for a number of administrative processes.
Issues can also arise where errors in your documentation can cause an inordinate amount of hassle and stress, preventing you from accessing and completing necessary administrative procedures.