The terms are actually quite reasonable. You can't even pay for your resources without changing your account type (anything you buy with your free credit gets wiped out after the trial month, only the "always free" stuff remains...) so I'm reasonably certain you can use their service quite comfortably.
The 50mbps uplink isn't spectacular and certainly not enough to run a business on, but for anything the other free tiers are intended for (experimentation and hobby use) it's sufficient.
Juet remember to never give them your credit card number and provide as little personal information as legally allowed. You don't want the lawnmower to come in your direction, the lawnmower doesn't care.
Four CPUs, 300GiB of storage and 24GiB of RAM should last for quite some time.
If you do need the compute and bandwidth: pay someone. Pay Heroku or set up a Dokku (or similar) system on your own server.