It adds 50% bonus at the end of each game, when the scoreboard appears. Just look at the bottom of the screen which shows Gold prem +50% etc...
However, prem weapons cannot be bought. Still you can use a 5th slot weapon( which is a premium feature). Also, you could use extra ammo feature which is again premium feature.
NOTE: if you already own a premium weapon, you can equip into your 5th slot. I have done this and it works just fine.
So, when these hacks give you these many premium features; I would not mind the lack of premium weapons added to it!!