at one site I played at the money you win from the free spins is then multiplied by 25 to become the wagering you gotta do but the catch is that you can only win the amount that you won from the free spins, so if for example you won $0.80.. you would then wager 25 x 0.80 = 20 eur..... then once you finished the wagering, even if your balance had grown to 200$ during the course of the wagering, you would then only get $0.80 cash after they remove the excess. also they put a cap on how much you can win from the free promo spins of say 60 euros so.
recently I had won 6 eur from some 50 free promo spins at 0.20 . so had to wager 6 x 25 = 150 euros... but during the wagering had some good wins, got balance over 218 euros. then when I finished the wagering I still had 176 eur but they immediately reduced it to just 6.00 eur cash.