It'd be pretty hilarious if GoLand switched to a mobile pricing model where the IDE is free... But you have to use build gems to run things. You get a fixed number of build gems a week then you can buy more fro $9.99 or $19.99.
Your debug gems would recharge after watching a short ad.
In principle yes. That's because you want your players to be hooked before you first present them with the prospect to pay for an advantage. So you ensure a specific action is ingrained in muscle memory before it requires payment.