I just discovered to my utter dismay that I was paying for Plus membership (for over a year), thinking that it is required to access PlayStation Shop. I would have continued to do so, but luckily I saw a YT video, where it was explained that I have free games each month given by Sony.
I was stupid and assume things, which is my fault totally. Now, for the March 2018 I saw BloodBorne given for free, which made me very happy (as I wanted to get that game anyway). Also, I checked the previous 'giveawys' and there are some titles I would want to have. Is there a way to get them 'retroactively'?