Vertopal offers plans for you. By choosing each plan, it will allocate to you different resources, limits, priorities, and speeds, and provide different features.
You can get more information on the pricing page.
The user with a free plan will benefit from more resources, conversion speed, priority, and fewer limits than the guest plan.
The premium plan allocates you the highest values, which means, more resources, conversion speed, priority, and fewer limits in the premium plan are several times better than the free plans. also, in the premium plan, you have access to special tools and features. You will also be able to use premium services such as API.