Being a Master student at LTH you should, from the 2nd semester until you apply for your degree , register on your programme at the beginning of each semester. This is a way to show that you intend to continue your studies in the programme during the current semester. You make the registration on the web in LU's Student Portal.
If you do not register on the programme it will neither be possible for the departments to register you on the courses you have applied to nor will they be able to report the results of your exams.
The semester registration is also necessary for you to be covered by the university insurance and qualified for CSN (mainly Swedish students).
This means that you should register yourself even if you only take re-exams or are working on your thesis.
An email reminder is always sent when the registration opens (one week before the start of the semester). If you have not finished your studies on time and it is your fifth semester, you need to re-register for the fourth semester.