If you click F4 that’s the preview shortcut if you click it and wait to the preview comes up and click it again you got 2 previews at once
That’s what it’s supposed to do. What you are looking for is F5.
on mine its F4 but you got infinity without indie or pro
you can run as many previews as you want. It is not a subscriber only function.
to run another preview without F4, right lick on the preview button and click launch another preview.
That is intentional. There is no cost associated with running previews. If you mean the popup that shows up mentioning the subscription, if you read it, it is just talking about it being available and asking you to consider supporting the engine.
It does not say you have to subscribe, and there is a button right there to continue.