New features and refinements are added to Videopad several times monthly. Versions don't expire and updates after purchase are free for six months.
Yet there's no need to update if the program is doing the job. Newer versions can always be test driven to check out new features, and quirks.
Unlicensed Videopad releases function indefinitely in most cases, but features are limited. There are no watermarks in the unlicensed versions.
Always retain purchase registration info for reinstall when desired. Did the linked release solve your audio issue?