Does go sms put charges in your bill for sending and receving text or sms messages

[AC Question]

I was enjoying this app these past couple days until I got a message saying that I could save noeu and try their go chat version or whatever I text A LOT and now in worrrjed there's going to be huge charges on my phone when I had no idea it cost I tried to do research after all that but I can't find any clear answers I'd the apps charges to send and receiver SMS and mms messages any help would be appreciated