L must give T notice of intent to terminate the lease at least 30 days before T's next rent payment is due (30 days before 8/1), UNLESS L has actual knowledge or reasonable belief that T or T's guest has violated a controlled substance law while on the leased premises. [5321.17] "Actual knowlede or reasonable belief" if either police have executed a serach warrant for drugs & found them & notified L they found drugs, OR a court determines after a hearing that T more likely than not violated drug laws. If police haven't caught you with drugs at home, L can't evict you on 3 days notice.
I couldn't find any law requiring L to give you a receipt for cash rent payments. However, if L has always demanded cash and you've been there for some months, L will have a hard time arguing that you haven't paid any rent the whole time. I hope you can produce some sort of bank records showing that you withdrew the rent money in cash every month just before rent was due.
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This is not legal advice and you are not my client. Double check everything with your own attorney and your state's laws.