Players Union membership is paid on an annual basis, and each time you renew, you get the shirt for the year your membership would have expired had you not renewed (assuming you don't choose the "Membership with no shirt" option).
You can purchase Players Union membership for up to 2 years into the future.
'Laughed at this!' 5 min
'Alvarez neck' 1 hr
'Swing 42' 5 hrs