Answer from Weld County:
Weld County permits are valid for three (3) years, but only expire after that period if construction has not started. Once construction begins, it is then treated as an "active" site. Active sites are then held to conditions and development standards for the life of the Location. Active Locations and their permits do not expire, until the Operator chooses to plug and abandon the location, which can be and usually is multiple years after production begins.