Lemmy.ca runs on donations, It is ultimately up to the admins of each instance to decide how to monetize each instance.
Currently Lemmy.ca costs about 25$/mo to run. Although given all the growth that seems like it's out of date. You can donate here or here. Tallying up both donations reported values (remember that the donation site probably takes a cut) the instance makes 150 a month from 30 users, so we are more than set for the next little while.