1, never buy acs from leechers etc..
2, buy accs from trusted persons ,that have sold like 10+ accs on sythe ,try to contact prevvievous buyers and ask them if accs wasnt recorvered
3, if u are buying acc ,than use MMer that will try to recover acc with info from seller and if it sucessfull than u can trade with seller
if he want to recover it back , its very easy. what you ve done can't 100% assure your acount security .
and jagex may lock account if they detective the account jump to another country .
I've always found, an account can be recovered with just credit card details. So if you pay for membership using credit card, that might increase your chances of it not getting recovered next time.
No your not "SAFE", any bought account can be recovered by the original creator if he still knows first passwords, and has a agreement and transaction Id's.
But if you can trust a stranger(or who ever sold you the account) you have nothing to worry about.