You can come and leave whenever you want, just be aware that to get the ASLS certificate you will need to attend the full course, and pass the written and practical exams, which will be held on the last course day.
In other words, anyone being absent during the course will NOT get the full course certificate. Instead you will receive a printed "Proof of Attendance", still eligible to apply for educational points. In order to receive the Advanced Surfing Medicine Life Support course certificate participants need to fulfill ALL the criteria as stated in the course's Terms & Conditions.