Encryption/Decryption of a file

Question

Hi All, I am going to develop a small software which searches from the database. Since the data is small, I thought of using EXCEL or CSV, but now my problem is when I sell the software, I dont want the users to view the file and data. My purpose of application is to search the year of a product from its ID... User enters the product ID and the application returns the year... Well the data consists of Product ID and Year... only two columns... But the rows may extend to 5000. Since its a small application I dont want any big databases like SQL . But my data has to be secured. Any idea would be appreciated