Are the labs in AWS Solution architect Professional course within AWS free tier?
Short answer: No.
Much of what’s in our AWS Certified Solutions Architect – Professional course can be completed within the free tier, or involves using services that have no cost overall. However, there are some services like Kinesis which has no free tier, and some of the HA labs where you can quickly incur costs outside of the free tier.
On the question of which labs incur costs, and how much it would cost, as a Pro-level course, this is something you legitimately do need to be able to answer during your own studies. Working as a Solutions Architect, one of the most important roles is assessing a given solution, including its cost-effectiveness.
Fortunately, it is quite simple to do a check on the pricing through the AWS Website for a particular service. You can also keep prices extremely low by only running the labs for as long as you need them. Most of the excessive costs of labs comes from leaving things running for extensive periods of time (said by someone who has had a nice surprise $400 AWS Bill because he forgot to terminate things)
Yes, the key is terminating (or at least stopping) the instances. Sometimes you may forget, or feel lazy – the exercise is not yet complete and you want to not start form scratch next day – you let it stay on. You can easily get a good bill.