Using a shared SEMRush account

I found a guy on fiverr selling a shared SEMRush account for very cheap. His English isn't great so I'm having trouble getting my questions answered. Is this sort of thing a good idea?

If I have a shared account, does this mean someone who is sharing can come in and delete my data or start messing with it? SEMRush has credits and monthly limits for keywords and stuff. Could one greedy person use them all up for themselves and leave nothing for everyone else?

When you use share account, you obviously expose your details to others as well. If you do not want others to see, the only option would be to delete those data after you are done.