it will only give you a fresh new level regardless how much % of exp you had before it will vanish.
Since you're at 50% and tomorrow is new week, just wait and use it on lv 69 instead

the upgrade ball doesn't work after level 60.

Oh? sorry then! my bad might aswell use it now. but yea it will just fill up your exp bar to get level up

Thanks for the fast reply, so that means it should be used right when you reach lvl 59 to save the most experience

It will level you up straight to 60, since you are 59 now, no matter how much % you have on exp bar. It always just let you skip to next level. And as mentioned before- it don't work after you hit lvl 60.

yeah, best to use it as soon as you hit 59 it gives you an entire level regardless of experience required and as Ravenia said if you are half alhrough a level that half level of experience is essentially wasted.

Hi! my Friend is Level 59... and used the pill.. he didn't level and only received small amount of EXP... :@