There's no limit imposed by Riverside on a recording session's length.
However, for best results, it's highly recommended for recordings to be under 4 hours in length.
If you are planning to have a long recording session, be sure to review our best practices recommendations to ensure a smooth recording session.
NOTE:
If your account uses Riverside's free plan you can download up to two hours of recordings as separate High Quality tracks. You can also use the Editor to customize and export combined recordings without any limit.