So if i cancel the plan do i loose my pictures??

I see, from Downgrade or cancel your iCloud storage plan - Apple Support

What happens when you downgrade your storage plan

If your iCloud storage exceeds your new storage plan capacity, iCloud won't sync or update your information. iCloud updates again when you increase your storage capacity or delete information to make more space. To make sure you don't lose any information, learn how to back up what's in iCloud. To help free up space, learn how to delete information that you don't need anymore.

If you downgrade or cancel your plan, the storage change takes effect after your current subscription billing period ends.* If you downgrade to the free iCloud Storage plan, you'll have 5GB of storage.

So if I understand it correctly, data will not be removed. But this policy may be changed by Apple at any moment in future.

According to this Apple iCloud Support page:

If you downgrade your storage plan and your content exceeds the storage you have available, new photos and videos won't upload to iCloud Photo Library and your devices will stop backing up to iCloud.

iCloud Drive and iCloud-enabled apps won’t update across your devices, and you won't be able to send or receive messages with your iCloud email address.

To use iCloud after exceeding your available storage, remove backups, photos, documents, or email messages you don’t need. You can access photos, videos, and documents for 30 days after you delete or disable iCloud Photo Library and iCloud Drive.