So, I have an issue, I want to add permissions to people temporarily, like 30 days or something, but when I use " pex user Producting timed add essentials.kits.dealer 86400" they get the kit at first, but if the user relogs, they lose access to it again.

pex 1.x is no longer supported, pex 2.x will allow timed permissions to be given persistently though.