This is a user forum, not an Adobe support forum.
You don't give enough information for anyone to help you much. Did you purchase the software in question?
Since all or most Adobe apps can be downloaded at no cost as trial versions for evaluation, when you purchase the software, what you are purchasing IS your serial number, which will allow you to use the software beyond the trial period. This is something you should store safely, and keep long-term.
If you haven't purchased the software yet, you should do so, and then you will receive your serial number.
If you have already purchased the software, and received your serial number, but lost it, then you should contact Adobe Customer Service. They probably have a record of your purchase and MAY be able to supply your serial number again.
Adobe Customer Service: https://helpx.adobe.com/contact.html