As long as the payday loan company is legit that you're promoting through the affiliate programs then they can be trusted.
Make sure you do your research on the affiliate program and payday loan company you're promoting with the affiliate company and you should be paid out by them.
A few good trusted payday loan affiliate programs are
https://www.lendup.com/payday-loan-affiliate-program and
https://leadsgate.com/
I've been paid on time by both of them affiliate programs promoting payday loans and never had any problem with them.