GCX Cash does expire. Cash earned from making purchases on Exact Pay will expire two years from the transaction date, while the Cash earned from referrals expires 6 months from the referral. Other earnings will have their expiration timeframes.
To view the expiration date of your GCX Cash via the GCX Website, navigate to 'My Account' in the top right corner and click the 'My GCX Cash' option. If you are viewing your GCX Cash expiration via the GCX App, Select the icon that presents your name at the bottom and navigate to the 'GCX Cash option.