Used to

1. Used to + invinitive in only used in the past : it has no present form we use it to talk about pas habits which are now finished. for example : i used to smoke, but i've stoped.
2. In formal style, used to can can have the forms of a modal auxiliary verd. for exalple:

Did you use to play football at school? (informal)

Used you to play football at school?(formal)

I didn’t used to like sinetron, but niw ido. (informal)

I used not to like sinetron, but now I do. (formal)

3. We do not used to to say how long somethink took, or how often it happened.

I live in Jakarta for three years

(not I used to live in Jakarta for three years)