Is there any differences between free version and 8,99€ version? I'm now using Myibidder free version and it offers 20 free snipes. I like this apps and wondering to have more snipes. Thank you for any advices.

I assume you refer to iOS app.
The "PPS" version comes with 20 snipes and you need to purchase more snipes whenever you need it. That's like pay as you go and works best for ocasional sniping.
The other version offers unlimited sniping and works best for heavy sniping.