You can let your customers to try out your product or service for a limited period before switching them to paid subscription. Trials create an order but not the billing invoice until the trial have ended.
Using Free Trial option you can set the number of trial periods an order can be on trial mode. Once the trial period is over, Omnibasis automatically converts it to an active subscription and attempts to process the first payment.
Trial period can be any of Hour, Day, Week, Month, Year