How To Protect The PDF File

Hello friends, I am Gregory and I am a new member on this forum. I have created a file from PDF creator and it's a very important file that I need to save it for a long time. So I am thinking about how to protect the file. Could anyone please suggest about this? Any kind of suggestions will be highly appreciated. Thank you,

This is very informative info that I found online. The most essential point which discussed an article that encrypts the PDF file. Normally I installed Smallpdf to protect my data. If anyone wants to do it, there are more software and tools available on the internet, can check out. I install Smallpdf which is quite easy to use.