Hello!
Can I submit my game to Steam, if I used the free version? Or I can only do that with Unity Pro?
Thanks!
Yes you can…
The real question however is can you make a game good enough for them to accept it 
Welcome to the forums!
Thank you
I hope I can make a good game 
Just remember the EULA restrictions for Unity Indie(free). You cannot make over $100,000 annually from a published game unless you have Unity Pro. If you start to make some money off your project I am sure you wouldn’t mind getting all those nice features anyhow with a purchase of the pro license ;).
If I earn at least $50,000, than I will buy Unity, with the nice plugins