For Question #1: Number of Instances
Amazon charges based on hours of usage, not based on number of instances you are running. Check this Amazon AWS Free tier details.
They have clearly mentioned that the free tier includes:
750 hours of Amazon EC2 Linux/UNIX or RHEL or SLES Micro Instance usage (613 MB of memory and 32-bit and 64-bit platform support) – enough hours to run continuously each month*
750 hours of Amazon EC2 Microsoft Windows Server‡ Micro Instance usage (613 MB of memory and 32-bit and 64-bit platform support) – enough hours to run continuously each month*
750 hours of an Elastic Load Balancer plus 15 GB data processing*
30 GB of Amazon Elastic Block Storage, plus 2 million I/Os and 1 GB of snapshot storage
For Question #2: Elastic IP addresses
Allocating and using one Elastic IP addresses per instance is basically free, except if the Elastic IP address is not currently associated with an instance, see section Elastic IP Addresses on page Amazon EC2 Pricing:
$0.00 for one Elastic IP address associated with a running instance
$0.005 per additional Elastic IP address associated with a running instance per hour on a pro rata basis
$0.005 per Elastic IP address not associated with a running instance per hour on a pro rata basis
$0.00 per Elastic IP address remap for the first 100 remaps per month
$0.10 per Elastic IP address remap for additional remaps over 100 per month
Answer from Dineshkumar on Stack OverflowEc2 free tier?
Amazon EC2 Free tier - how many instances can I run - Stack Overflow
Ec2 Instance type: What is the difference between "Free tier available" and "eligible" ?
New AWS Free Tier launching July 15th
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Hello! I'm currently working on a Unity game. The only problem is servers. I have been looking at EC2, but don't want to spend money on this project. To start, Does EC2 with the free tier get deactivted after 12 months? If it doesn't, what would force me to pay for it?(Server being up to long, Too many players connecting etc)
For Question #1: Number of Instances
Amazon charges based on hours of usage, not based on number of instances you are running. Check this Amazon AWS Free tier details.
They have clearly mentioned that the free tier includes:
750 hours of Amazon EC2 Linux/UNIX or RHEL or SLES Micro Instance usage (613 MB of memory and 32-bit and 64-bit platform support) – enough hours to run continuously each month*
750 hours of Amazon EC2 Microsoft Windows Server‡ Micro Instance usage (613 MB of memory and 32-bit and 64-bit platform support) – enough hours to run continuously each month*
750 hours of an Elastic Load Balancer plus 15 GB data processing*
30 GB of Amazon Elastic Block Storage, plus 2 million I/Os and 1 GB of snapshot storage
For Question #2: Elastic IP addresses
Allocating and using one Elastic IP addresses per instance is basically free, except if the Elastic IP address is not currently associated with an instance, see section Elastic IP Addresses on page Amazon EC2 Pricing:
$0.00 for one Elastic IP address associated with a running instance
$0.005 per additional Elastic IP address associated with a running instance per hour on a pro rata basis
$0.005 per Elastic IP address not associated with a running instance per hour on a pro rata basis
$0.00 per Elastic IP address remap for the first 100 remaps per month
$0.10 per Elastic IP address remap for additional remaps over 100 per month
It says,
750 hours of Amazon EC2 Linux/UNIX or RHEL or SLES Micro Instance usage (613 MB of memory and 32-bit and 64-bit platform support)
To clarify, if you have 2 EC2 instances run 24/7, that will make them a total of 1,488 hours in 31 days (1 month)
24 hrs * 31 days = 744 hours.
744 hours * 2 instances = 1,488 hours
If you don't want to pay an excess. Your 2 instances would only last around 15 days so it won't exceed 750 hours allocation per month.
Furthermore, this free tier expires in 12 month and only for new customers following your AWS sign-up date.