A method of managing software use in a desired mode and with ease of handling upgrades or other changes includes a sales company or other software provider adding a password to software, inserting identification information into a dongle, and distributing the same to users. A secret key and an open key are prepared and the open key is transmitted to the user. When the user tries to obtain a license, the password is sent to the sales company. The sales company detects identification information based on the password, encodes the same by using the secret key, and sends the same to the user as encoded license information. The user decodes the encoded license information by the open key and matches the same against the identification information included in the dongle. If the information match, the software effectively starts up, while if not, the execution of the software is stopped.