Also, if I decided to drop all my subjects (hypothetically), do I still have to pay the matriculation considering that I am technically not enrolled?

Nope. No refunds will be processed 4 weeks after the registration period have passed even if you dropped all your subjects.

Students who have paid their matriculation fees and who withdraw their registration or are granted honorable dismissal or leave of absence shall be entitled to a refund of their matriculation fees, except entrance and registration fees, in accordance with the following schedule:

• Before the opening of classes: 100%
• Within one week from the opening of classes: 80%
• Within the second, third, and fourth week from the opening of classes: 50%
• After the fourth week: No refund