That stuff is in the FARs under the Part that covers the operation eg Part 91, 135, 121 etc.
US certificates & ratings (ie licences etc) are issued permanently however are not valid for use unless you've met certain recency &/or refresher requirements.
A Biennial Flight Review is one of these requirements. Basically a refresher flight done at least every two years to review your skills. As best I recall it involves at least an hour ground time & the same in the air. You don't lose your licence if you don't do one, but it effectively becomes dormant. Just about any flight test for the issue of another certificate or rating meets the BFR requirement, as do company base/line checks. My impending Part 135 checkride will, for example, as did my ATP-Single Engine Land & Single Engine Sea certificates that I did late last year to revalidate my long unused multi-engine ATP
Instrument rating privileges - either as a separate rating on a PPL or CPL, or the integral IR privilages included with an ATP - need you to have met the recency requirements such as 6 approaches in 6 the last six months etc.