One thing that I did note in looking through the site was:

GlobalPass mileage does not expire as customers remain active. All earned mileage will expire if the account does not reflect a qualifying activity within 36 months from the last Service Date.

Qualifying activity is defined as earned mileage credits on a GlobalPass participating Service Provider or transferring miles INBOUND from a Participating "Transfer" Program.

Transfer of miles OUTBOUND to a Transfer Program is not considered a qualifying activity.

What is great is that a transfer in will keep the miles active. I did not realize this from Latinpass. Also it is interesting that they use the term "Service Date" the term is capitalized so I assume it has a definition which is not listed. Would a Service Date be the issuance of a reward ticket? Well anyway, I will be transfering in some miles to make sure the others do not expire.