transfer an invitation from my free account to my other paid account

Sorry, @izza, its not possible to transfer a meeting between a paid and unpaid account.

There are ways to transfer Zoom sessions using Scheduling Privilege, which requires both accounts to be paid. The only other way I’m aware of is you can designate an account to receive meetings belonging to an account you are about to delete. If your Basic count is on the same organizational account as your paid account, you might be about to do this – but I haven’t tested it, so can’t say for sure.