It depends on what you need. All Plugins are free to use with upgrades available for premium features. Upgrades can be purchased in the POWr Editor. Pricing for each plan works as follows:
Free Version - 100% free, forever, for everyone
All POWr Plugins are available for free, forever. You can use as many of them as you'd like, on as many sites as you'd like. Free versions are great for getting started. If you want to remove the POWr logo, or get access to plugin-specific premium features, consider an upgrade!
Note: Discounts are available for annual and biannual plans.