There are a lot of reasons why people choose to migrate to other countries. For most people, it's to satisfy the subjective wellbeing that we all seek.  While visiting Tanzania as a Tourist you are granted at 90 Day Visa. After the 90 Days you have two options, re-apply of extension or exit/enter the country (Only if you have a Multiple Entry Visa). 

If you'd like to apply for a resident card, there are three categories that you must apply under. 

1. Class A: Issued to employed foreigners. 

2.  Class B: Issued to foreigners employed by companies or institutions.

3. Class C: Issued to other foreigners such as missionaries, students, volunteers, researchers or retired persons.

For full information and specifics please visit the Tanzania High Commission website at https://ke.tzembassy.go.tz/services/category/permits-and-registrations

Other specific questions can be answered by your Local Tanzanian Embassy in your Country.