Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
Resigning: Notice Periods
If you want to quit your job, you cannot just walk away. If you have worked for less than 2 years, you must give 30 days' notice. If you have worked for more than 2 years, the notice period is 60 days.
You must send a registered letter to your employer. If you leave without giving notice, the employer can legally deduct the pay for the missing days from your final settlement.