Restricting access after number of plays

I would like to be able to put a restriction or limit the number of times someone accesses one of my games. It may be this needs to be done on the actual website rather than within the game, but is there any way you can use code on certain paragraphs that would someone restrict access once a person has played say, five times?

There may be a number of ways to do this, but I am very new to this so any ideas or suggestions are welcome.

It may be that they need to enter an email address at the beginning (another answer required on how to do that!) or that it someone registers the local machine IP.

Any suggestions gratefully received. Twine 2.1 Mac OS.

Many thanks