for the trial accounts you can just have a noobie isle if need be depending on how the game mechanics work problem solved.
off course it could be that if you wander across a camp that was built up buy a trial account user who has now left. your presented with options do you capture it and sell everything for resources or keep it and use it to your advantage or burn it to the ground and slay the villagers to up your kill count
i personally prefer a monthly sub its just simpler you pay 12 months subscription and forget about it till next year also means game designers dont waste time on designing micrtransactions or how they will work.
plus as some one already mentioned we get a better product.