The foreign citizen must register in the migration office of the place of residence not later than three months from the date of receipt of the permission for permanent stay. An important condition is to reside in the Republic of Belarus only at the place of residence indicated in the permission for permanent stay.
Also you should pay your attention on 2 things:
1. You have to stay on the territory of the Republic of Belarus more than 183 days per year. If you don’t do that migration office will have the right to cancel your permission for permanent stay in Belarus.
2. After you get permission for permanent stay in Belarus you will automatically become Belarusian tax resident. It means that you will have to pay taxes same as Belarusian citizen.
This is the example of permanent residence permit: