You can get a regular ticket for €8.50, in case you have a group of 10+ people, then the price is €6.80 per ticket. If it’s a child of 0-12 years accompanied by an adult, then it’s free (€0.00). Besides that, you can use a discount in case you have one. If you know the date of your travel, then you can book a ticket or tickets on a certain date and even choose a time. You have a year to attend the museum — it’s how long the tickets are valid after the purchase.