When you subscribe to AStats, you agree that your steam data will be read by, stored by and shown on AStats.

AStats will use the steam public XML and HTTP pages to read data and can use the Steam Web API once you subscribe and thus giving permission for that.

AStats reserves the right to change the Terms of Use, and you are responsible for regularly reviewing these Terms of Use.
Your continued use of the AStats after the effective date of such changes will constitute acceptance of and agreement to any such changes.
If you don't agree with any such changes, or to any of the terms in this Agreement, your only remedy is to stop using AStats.

AStats will not sell, trade or give away your information, like email and passwords to third parties.
The password you use on AStats is not stored, instead an encrypted hash is made and stored and that is used to compare with your password to login.
At request, your member profile may be disabled, making it unavailable to other users, final decision what to disable or not is up to the moderators.

There is a cookie for storing your profile settings and an encrypted password. And also one from Google for Adsense (the ad banners) and Analytics (so we can see the web site visitor statistics).

If you have any questions you can ask them at the AStats forum or on any of the other public channels.