Well you can simply use a counter
\documentclass[12pt,a4paper]{article}
\usepackage{xskak}
\newcounter{chessex}
\newcommand\printchessex{\refstepcounter{chessex}\thechessex}
\begin{document}
\chessboard\hfill\printchessex
\chessboard\hfill\printchessex
\end{document}
But I would suggest one of the packages for question/answer sheets, e.g. answers or exams.
As Ulrike Fisher suggested in a comment, something was missing in the code: the first moves of the game. skak can follow the moves from the beginning as if was playing and print the chessboard at the final state as well. Additionally, you can set the chessboard by putting every single piece on its own square and then print it with some relevant moves and comments aside with the written moves. For those purpouses, xskak is an improved version of the package, since corrects some bugs detected and adds some other features (see xskak: An extension to the package skak)
When displaying only move games, you must write them from the beginning or, from some move to finish.
I did both in the code. First column is the complete game with all the moves (I retrieved the information on Stolberg vs. Botvinnik game). Here xskak plays the game -as Fisher said-, and returns the final possition with \chessboard command.
Second column is what you were pretending. But in this case -since xskak does not know how to interpret the last 7 moves of a game without preamble and middle game, would place pieces in positions that could overlap each other on every square-, you needed to write a command to tell xskak to forget first moves and displays last ones by typing \xskakset{defaultmoveid=35w} (p.28, CTAN xskak), and then you can settle by hand the pieces on the chessboard with the final positions if you want.
Your code generated two errors, one because of the last moves written and second, due to 0--1 at the end of \mainline{...} (this one caused the error The control sequence ... was never \def'ed). You should write the key result=0--1 inside \newchessboard and call it after \mainline{...} with \xskakgetgame{result}. There is no need to put \, to separate moves within this environment.
\documentclass{article}
\usepackage{ragged2e}
\usepackage{chessboard}
\usepackage{xskak}
\textwidth=17cm
\oddsidemargin=-1cm
\begin{document}
\begin{minipage}{0.4\textwidth}
\centering {\large\bf Stolberg vs. Botvinnik}
\justify\newchessgame[white=Stolberg,black=Botvinnik]
\mainline{%
1. d4 Nf6 2. c4 e6 3. Nc3 Bb4
4. e3 O-O 5. Bd3 d5 6. cxd5 exd5
7. Nge2 c5 8. O-O Nc6 9. a3 cxd4
10. exd4 Bd6 11. h3 h6 12. b4 Re8
13. Qb3 Be6 14. Bd2 Qd7 15. f4 Bf5
16. Qc2 Be4 17. b5 Bxd3 18. Qxd3 Na5
19. Ng3 Nc4 20. Bc1 Rac8 21. Ra2 Bf8
22. a4 Bb4 23. Nd1 Ne4 24. f5 Nxg3
25. Qxg3 Bd6 26. Qf3 Be7 27. Qg3 Bf6
28. Bxh6 Bxd4+ 29. Kh1 f6 30. Bc1 Re4
31. Qd3 Ne5 32. Qb1 Rc4 33. a5 Bc5
34. b6 a6 35. Nb2 Rc3 36. Bd2 Rb3
37. Qc2 Qb5 38. Rc1 Bf8 39. Rd1 Re2
40. Qc1 Rxh3+ 41. gxh3! d4}
\chessboard
\end{minipage}
%
\hfill\vline\hfill
%
%Last 7 moves
%Chessboard has to be set by hand with keys \newchessgame[setwhite={...},setblack={...}]
\begin{minipage}{0.4\textwidth}
\chessboard
\vspace{5mm}
\centering {\large\bf Stolberg vs. Botvinnik} \\ (last 7 moves)
\justify\xskakset{defaultmoveid=35w}
\newchessgame[id=A,white=Stolberg,black=Botvinnik,
setwhite={pa5,pb6,pf5,ph3,ra2,rd1,nb2,bd2,qc1,kh1},
addblack={pa6,pb7,pd4,pf6,pg7,bf8,ne5,re2,qb5,kg8},result=0--1]
\xskakgetgame{white}--\xskakgetgame{black}: %Competitors names
\mainline{%
35. Nb2 Rc3 36. Bd2 Rb3 37. Qc2 Qb5
38. Rc1 Bf8 39. Rd1 Re2 40. Qc1 Rxh3+
41. pxh3! pd4} \quad\mbox{\xskakgetgame{result}}
\end{minipage}
\end{document}
Best Answer