The Travellers Prepaid Data SIM Card gives you 15 days of 30 GB of internet to use. After this period you will need to top up to continue using the internet.
If you top up during the validity period, you will override the validity according to the new top-up value.
These are the top-up options:
You can see here further information about these plans in portuguese
If you are Visiting Portugal find here the best way to stay connected
International Add-ons – Find here international calls at a lower price