Playing two accounts is super easy once you get into it.
I play two accounts legit, one is my main used currently for Raids 1 + 2, while often doing something like rune dragons/gargoyles on my alt which works well, after a few hours of doing it you get into a rhythm where both accounts are being progressed at minimal effort.
+Playing those two accounts works well with what I use osbot for, while not doing anything major on there I'll run whatever I need to on other accounts I have and this keeps my botting time minimal but with efficient rewards.
TL;DR, Find something that can progress your 2nd account while not being too tedious to your primary account, the best option is fishing for example but the end reward isn't really too good (in terms of gp/hr or unlocks)
EDIT -
Also don't treat that bought account like a new main, progress YOUR main and use the higher level CB to do the highest tier gp/hr money maker possible for example, that way you get the use out of it to pay for the $$ you paid for it.