If you have W3 Total Cache plugin. You need to add some pages to the “Never cache the following pages:” list on Page Cache, Minify and Database Cache setting pages.

These are;
register
transactions
payments
login
download
lostpassword
subscribe

If you changed any of the links above for your site, then you’ll need to add them also.

If you have other cache plugin, just add the pages listed above to their do-not-cache lists.