AWS Workspaces access Log

Is there any way to check on aws cloudwatch? I wonder how I can do it for free rather than using a separate service.

There are a few ways to do this. The most detailed way is with cloudwatch metrics (https://docs.aws.amazon.com/workspaces/latest/adminguide/cloudwatch-metrics.html). The UserConnected metric will show you exactly when the workspace is in use so long as the user is connecting using the workspaces client. Alternatively, if you just need to perform a quick spot check, you can go to the workspaces console and look at "User Last Active" for the specific workspace. It provides less detail and, in my experience, is slightly less reliable. Still it gets the job done. Finally, if this is something you'll do regularly, you can deploy the Workspaces cost optimizer (https://aws.amazon.com/solutions/implementations/cost-optimizer-for-amazon-workspaces/). it can generate daily usage reports for every workspace across all of your accounts/regions and dump them into S3 for you.

You can use the Amazon WorkSpaces Application Manager (WAM) usage reports to see the last time that a user launched an application from their WorkSpace. These reports provide information on application usage, including the number of times an application was launched and the last launch time for each user. Here is a link to AWS official documentation -> https://docs.aws.amazon.com/wam/latest/adminguide/what_is.html

You can use Amazon CloudWatch to track the last time that a user accessed their Amazon WorkSpaces. However, please note that this will require you to enable logging for WorkSpaces. Once logging has started, you can view the logs in the CloudWatch console. You can use CloudWatch Logs Insights to query the logs and find the last user access time.