its valid for 5 years on the terms that the stamp says 5 years. The thing that worries some people is that upon entry to Thailand the immigration officer has discretionary power to refuse entry for any reason. Its rare but some customers have been asked to prove ongoing soft power course attendance.
For those who are anxious we have come up with our DTV plus course.
The ask:thailand community, consisting of multiple Q/A groups with over 100,000 members, powers this platform. It is not an official government resource. Our members actively contribute to this resource, and while we strive for accuracy, we cannot guarantee its complete reliability. Assistance to travelers is provided as a community service.