Welcome! Serviio offers a 14 day free trial for the features of Serviio Pro, the paid version. After the 14 days pass, the Pro features are disabled but Serviio remains completely functional for the majority of its functionality. Unless the extra features of Pro are worthwhile for you, the free version will continue to function just fine forever.
To see what Pro offers over the free version, look at this page:
https://www.serviio.org/buy-pro/10-unca ... ree-vs-pro