The information below is taken from the City of Riverside, CA website
Do I need a City of Riverside Business License?
If you are a business entity doing business within the City of Riverside, then Yes, you will need to have a valid City Business License. If you have specific questions concerning Business Licenses in the City of Riverside, contact the Business License Division at (951) 826-5465.
What about Workers’ Compensation Insurance?
Contractors State license law requires that all California licensed contractors maintain Workers’ Compensation Insurance coverage if they have employees. The law also requires that the contractor present the Workers’ Compensation Insurance Certificate to the Building and Safety Department at the time of permit issuance.
How long is a permit good for?
A building permit is valid for 180 days after it is issued. In addition, a 180 day extension may be granted by the Building Official. In most cases, a permit will not be expired unless the applicant has failed to call for an inspection and show progress on the project for a 360 day period.
Once a permit is expired, you may be required to begin the permit process from the beginning and pay all of the applicable fees again, so it is wise to avoid permit expiration.