I hope this message finds you well. To directly address the issue, the source code is indeed intellectual property of you and your company and you should require a fee for its use. Decide what an appropriate fee would be based on the market and work to develope this intellectual property and ask this fee for use.
The handling of this arrangement should be done in a small contract that does a few things:
The contract does not have to be big, just needs to address the essential aspects as detailed above.
I hope this helps and best wishes.
You absolutely have the right to charge for the source code unless the specs and initial contract specified otherwise. Moreover, the company should expect to be charged for the use of the source code. Intellectual property is high dollar stuff, especially in your area of expertise and you should protect it with diligence and be compensated accordingly.
Here is a template. You should sign and date as well as the individuals and have it notarized.
To Whom It May Concern:
This letter is to signify the mutual agreement between ____________(Hereinafter "seller" and _____________ (hereinafter "purchaser") to release ________________source code as developed through a contractual work relationship that has now expired. The terms and conditions for the transfer of the __________________ source code are as follows:
__________________________ Date ______________
DISCLAIMER: Answers from Experts on JustAnswer are not substitutes for the advice of an attorney. JustAnswer is a public forum and questions and responses are not private or confidential or protected by the attorney-client privilege. The Expert above is not your attorney, and the response above is not legal advice. You should not read this response to propose specific action or address specific circumstances, but only to give you a sense of general principles of law that might affect the situation you describe. Application of these general principles to particular circumstances must be done by a lawyer who has spoken with you in confidence, learned all relevant information, and explored various options. Before acting on these general principles, you should hire a lawyer licensed to practice law in the jurisdiction to which your question pertains.
The responses above are from individual Experts, not JustAnswer. The site and services are provided “as is”. To view the verified credential of an Expert, click on the “Verified” symbol in the Expert’s profile. This site is not for emergency questions which should be directed immediately by telephone or in-person to qualified professionals. Please carefully read the Terms of Service (last updated February 8, 2012).