Yes you can use same Paypal account to make different ahrefs account but you might face two issues:
1. Getting Charged
If you missed to deactivate the account, you will be charged with the amount. Though ahrefs team is really helpful, they will surely refund the amount.
2. Paypal Account Getting Banned
You account might get banned if you keep on doing the same thing again n again. Because in this case Paypal has to face chargeback.
Case 1 happened with me and that led me to think of case 2.