Productive offers you complete control over your costs and has plans to suit everyone's needs. To change your current pricing plan, any user with the admin role can go to Settings > Billing and click on Change Plan:

If there is a price difference, you'll see how much it is:

If you are on a Standard plan, you can start a Free, 14-day Premium Trial before making your decision, and you can switch back to your previous plan at any time.