Going to friends lecturers

Has anyone been in trouble for going to friends lecture? I been going to my friends lecture and we currently separated as my course is a joint honours and its really been helpful going to lecture as its filling gaps and things I don't know and would the get lecturer get in trouble and I'm promise I'm not stealing a person chair as there always free chairs and if there wasn't a chair I would not go as I do not want be seen as selfish. I wish I never chose a joint honour course and seems like I'm unable to change it

If you are registered at the same uni and they are not monitoring attendance then it is not doing much harm.
Seems like a waste of time when you could be studying for your own course though.

It’s definitely not a waste of time. The topic is my subject area. I have plenty of time to study and I still want to pursue a PhD so it’s important to me.