Oh yea put it in a label, FC should be at the beginning of your program so it doesn't get set to 0 every time, have your main loop gosub to it and then put return at the very end of the gosub loop:
ACLS
*Variables here with other loading and initializing stuff*
@MAIN
*code and stuff*
GOSUB @CHKFC
*more code stuffs*
GOTO @MAIN
@CHKFC
*insert code here*
RETURN
0そうだね プレイ済み