The prices quoted in-game are in Euros (€). If you go through the purchasing process, PayPal (which handles payments) will convert Euros into your local currency when charging your credit card. If you want a preview, you can use this currency converter: 1 EUR to USD - Euros to US Dollars Exchange Rate
Alternatively, you can wait for the Steam version to come out in a few days, which handles some of this automatically. You’ll need to install Steam first, though: Steam, The Ultimate Online Game Platform
No, all purchases are permanent. Previously, licenses were given out for free for testing services and were revoked when testing was done – this will not happen again.