The short answer
A static QR code is printed data. It does not contain a timer and Qwero cannot switch it off. If it encodes a web address, the scan will work only while that address still resolves to useful content.
Why a code can seem expired
The destination may have moved, a shared link may have been revoked, a domain may have lapsed, or a dynamic QR provider may have disabled its redirect. Physical damage, poor contrast, and an undersized print can also make a valid code hard to scan.
Make a printed code last
Prefer a destination you control, avoid temporary or permission-limited share links, preserve a clear quiet zone, and save the exact source project with a dated print proof.