However, one thing that I still do a lot is work with PDF files. I create text files in MS Word and save them as PDFs; I occasionally edit PDFs with Adobe Acrobat (although it's a bit of a clunky process: it's generally less of a faff to edit the original Word file and then export it as a PDF and overwrite the PDF file that requires editing) or if I haven't go thte .doc file, I use Acrobat to open PDFs that need to be edited and save them as Word files to get the data into a more accessible format.
Something that I have noticed happening a lot in the most recent releases of Acrobat (especially in Acrobat DC and in a of couple predecessors) when I try to save a Word file as a PDF is the irritating error message
PDF Maker Your request could not be completed. Adobe Acrobat DC licence has either expired or not been activated
I've gone as far as un-installing and re-installing Creative Suite (which, when combined with re-booting Windows a couple of times, can blow an afternoon) without success, which only adds to the frustration and loathing.
However, there is a simple fix (although it's not well publicised on the many Adobe forum threads posted by frustrated users who just want to make a PDF with their costly bloatware): in the Windows Task Manager, find the Acrobat.exe and acrotray.exe processes and kill 'em. Word will then be able to make PDFs again.
And that's all there is to it.