Some hosting providers are selling cpanel for dedicated servers for 25$ per month that means 300$ per year.

How is this possible? Cpanel offers 1 year license for 425$ .

They're most likely using that as a "loss leader", where even though they're losing money on that they will make it up in other areas.

When you buy cpanel from your datacenter, they are selling "internal" licenses.

When you buy cpanel directly from cpanel.net or from an outside distributor, they are selling "external" licenses.

They both work the same way, but the "internal" licenses are about half the price.

And when you buy 3 or more licenses, you get 20% off.