Hi I'm Brian and I'll try to help.
I don't see any evidence of Microsoft offering a senior citizen discount. Which particular subscription are you considering? Which features of Microsoft 365 do you need to use? Does the $30 refer to a monthly cost or a yearly cost? I know that Microsoft 365 Personal is $9.99 per month or $99.99 per year. I know that until recently, it was $69.99 per year. Is that where the $30 comes from? Are you aware that there are less expensive subscriptions that may provide what you need. For example, Microsoft 365 Basic is $1.99 per month or $19.99 per year. While Microsoft 365 Personal provides 1TB of OneDrive space and a 100GB mailbox while also allowing you to install the Office suite locally on your computer, the Basic plan provides 100GB of OneDrive and mailbox storage, which is often plenty for the average user. While Basic doesn't allow you to install the Office suite locally, it is available online through https://microsoft365.com/. I use the online versions of Office and I find them plenty capable and I don't mind using a web browser to access them. All my data is stored on OneDrive but I find it easy enough to make offline copies of the important files.