Thank you for letting us know of your concern about the reminders that you keep on receiving. I believe this concern has been already addressed since you have already contacted our Chat Support line.
In relation to your other concern about the compatibility issue between the later versions of Trend Micro Security to Windows XP, it is indeed correct that versions 2017 and 2018 no longer supports Windows XP.
However, you may still install version 2016 (10.0) of Trend Micro Security to your machine. You may go to this link for additional information. Although, this isn't a guaranteed protection to your computer and even by any other security software since Microsoft will no longer create updates, bug fixes and address vulnerability issues to this operating system.
We hope that you will be able to upgrade your system very soon for additional protection.
Should you have any other concern, please do not hesitate to reach out to us.