NO
Rewrite Rules:
   [ subseteq(nil,?ys) -> true,
     subseteq(cons(?x,?xs),?ys) -> and(member(?x,?ys),subseteq(?xs,?ys)),
     member(?x,nil) -> false,
     member(?x,cons(?y,?ys)) -> or(eq(?x,?y),member(?x,?ys)),
     eq(0,0) -> true,
     eq(0,s(?y)) -> false,
     eq(s(?x),0) -> false,
     eq(s(?x),s(?y)) -> eq(?x,?y),
     and(true,true) -> true,
     and(?x,false) -> false,
     and(false,?y) -> false,
     or(true,?y) -> true,
     or(?x,true) -> true,
     or(false,false) -> false,
     subseteq(?xs,?xs) -> true ]
Apply Direct Methods...
Inner CPs:
   [  ]
Outer CPs:
   [ true = true,
     and(member(?x_1,cons(?x_1,?xs_1)),subseteq(?xs_1,cons(?x_1,?xs_1))) = true,
     false = false,
     true = true ]
Overlay, check Innermost Termination...
Innermost Terminating (hence Terminating), not WCR
Knuth & Bendix
Direct Methods: not CR

Final result: not CR
new/subseteq.trs: Success(not CR)
(18 msec.)