OK. You should update the original question you asked to include the fact that the server side code is using PHP and you'll probably get more targeted responses. Also, which database are you using and where is that being hosted?

Thanks, I'm planning on using MySql allocated in the own server as I'm using now in a free hosting server

I would use AWS, EC2 + RDS for now. A t2.micro should get you started. Make sure you automate the installation using Ansible (it's slow but you don't care, most importantly it's easy to pick-up and it's relatively agentless).

At this point, that's it IMHO. I wouldn't even use an ELB or auto-scaling at this point.

If you need help, drop a mail, I have spare time I can help you with the specifics (free of charge ofc).

ps. AWS has a learning curve and is not cheap but saves you a great deal of sysadmin management and most importantly, saves you from probable fire-fighting at this stage, plus there is the free tier will get you nearly a year without charges.