Paid actors are just like any other actor in Apify Store, just with a slight difference: in order to use them, you rent them on a monthly basis. Don't be put off by the fee, though. Paying to use actors empowers their creators to dedicate more time to them, which improves their quality and ensures maintenance.
Each paid actor comes with a free trial, so you can still determine if it is useful to you. After the free trial, the rental fee for an actor is automatically subtracted from your platform usage credits, similarly to, e.g. compute units. You always pay for using an actor in advance (for the following month). The payments begin when the trial expires, then recur monthly.
You activate a 7-day trial of an actor at noon of April 1, 2021. If you don't cancel the rental, you will be charged at noon on April 8, 2021, then May 8, 2021, and so on.
You can check your billing information in the Billing and usage section of Apify Console.
See our documentation for more details.