i bought exp 50% plus 90 days and exp 50% plus 30 days

It's not in the mall. if you already bought them. you don't activate them "in the match" but in the game go to your storage. then there will be a tab that says "items" click that and in there will be your + EXP 50%. (btw its not 90+30 at once. it stacks so its 1 item + 50% exp for 120 Days) click on it. and a new window will pop up and says "item affects are now active"

GL.

PS. play Gost Mode.