Adguard Reset Trial [exclusive] -

When you reinstall the software or delete local files, AdGuard’s servers cross-reference this hardware hash. If the server recognizes your device, the "new" trial is rejected.

Completely free and highly effective for web browsing.

Note: these describe common techniques; exact file names/paths differ by platform and AdGuard version.

Why the tolerance? Because AdGuard knows something its users forget: resets are annoying. Manually running a .bat file every two weeks, rebooting, reconfiguring filters, and logging back into browsers is friction. For most people, eventually, the friction wins. They buy the license.