On the Chordify website:
Log in to the My Premium page and the subscription information will be there.
On the Chordify Android app:
On the app homepage, click the 'Settings' icon in the top right-hand corner and scroll down to find your subscription information.
On the Chordify iOS app:
On the app homepage, click the 'Settings' icon in the top left-hand corner, then click 'Manage Premium' at the bottom of the page to find your subscription information.