The maximum possible time of using the program

If you never upgrade your computer equipment or OS, in theory you could use Acrobat indefinitely.  But that's not realistic, is it?

When the time comes, you have these modern options.

FREE Acrobat Reader -- view, comment & print PDF.
https://acrobat.adobe.com/acrobat/pdf-reader.html

Paid Acrobat Pro -- the complete solution for creating and saving PDF files.
https://acrobat.adobe.com/acrobat/acrobat-pro.html

Hope that helps.

[Moderator moved from The Lounge to Acrobat.]

in the future, to find the best place to post your message, use the list here, https://community.adobe.com/

p.s. i don't think the adobe website, and forums in particular, are easy to navigate, so don't spend a lot of time searching that forum list. do your best and we'll move the post (like this one has already been moved) if it helps you get responses.

<"moved from using the community">

that's unknown, at this time.  sometimes adobe announces its actions in advance, but sometimes events/hardware (esp, aging activation servers) force a loss of adobe's ability to help with older software.