Hi
From memory the Azure trial is a 200$ credit to use.
To give a approximate in the costing;
I have a low-end Azure VM (4g ram and normal HDD) that I use for a small webserver, and it cost me around 60$/month.
At that costing if you use the voucher I would guess you could run for 3 and a half months, but as I said it’s the bare minimum I have, if you need more ressource it can go over. I give that price for an estimate.