is it possible to use EC2 service and Lightsail service in the same time for a free trial account?

Hello,

Yes, it is possible to use AWS services to create free RDP (Remote Desktop Protocol) access during their respective free trial periods using EC2 or Lightsail.

1. AWS offers a free tier for EC2, which includes 750 hours per month of t2.micro or t3.micro instances (both Linux and Windows) for 12 months.
2. With Lightsail, you get 750 hours per month for 3 months of a Lightsail instance but Standard charges apply after first 750 hours of usage of the selected bundle each month.

References:

1. https://aws.amazon.com/lightsail/pricing/
2. https://aws.amazon.com/free/?all-free-tier.sort-by=item.additionalFields.SortRank&all-free-tier.sort-order=asc&awsf.Free%20Tier%20Types=*all&awsf.Free%20Tier%20Categories=*all

I believe you can take advantage of both offers, it's not an either/or situation.

Lightsail 3 Month Free Trial gives you 750 hours per month of the $8, $12, or $20 plans for free for three months when using Windows https://aws.amazon.com/free/compute/lightsail/

AWS Free Tier gives you 750 hours per month of Windows t2.micro or t3.micro instance dependent on region, for the first 12 months of your account https://aws.amazon.com/free/

750 hours per month is basically enough to run one instance continuously for the whole month. If you stop an instance when it's not in use then you won't be charged, and this means you can run more - e.g. two instances running for 375 hours per month = 750 hours total.

This is worth a read to explain how to avoid unexpected charges in Free Tier https://repost.aws/knowledge-center/free-tier-charges

And learn how to track your Free Tier usage https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/tracking-free-tier-usage.html