Manual plan grants show the wrong expiry date

TLDR

A customer was granted a 5-month plan on 26 August, but the billing page shows the wrong expiry date instead of January 2027. He noticed and asked, and support confirmed the date is wrong. Every manual grant with a custom length will show the same wrong date until fixed.

Done when

[code] Billing page shows the real expiry date for a custom-length grant - Check: a plan granted from the admin panel with a custom length (e.g. 5 months) - Expect: the trader's billing page shows the real expiry date (grant date plus plan length)
[code] Billing page shows the real expiry date for a default-length grant - Check: a plan granted with the default 90-day FTUK length - Expect: expiry shown = grant date plus 90 days
[human] The affected customer's account shows the correct expiry - Check: the affected customer's account (iriahus, Starter, granted 26 Aug 2026 for 5 months) - Expect: expiry shows late January 2027
[human] The affected customer is told it is fixed - Check: the affected customer (Featurebase #20) - Expect: told it is fixed

Out of scope

Letting the admin panel set an expiry date at grant time (https://trada.atlassian.net/browse/TRADA-1097#icft=TRADA-1097)
Downgrading FTUK users when the grant ends (https://trada.atlassian.net/browse/TRADA-1000#icft=TRADA-1000)

Tech context

Customer: iriahus (iriahus12@gmail.com). First granted Pro 10 accounts / 3 months, then changed to Starter 5 accounts / 5 months on 26 Aug 08:41 UTC
Two screenshots of the billing page are attached in the Featurebase conversation (31 Aug 07:06 UTC)
Likely the display uses the Stripe subscription period or a fixed 90-day default rather than the grant's own end date

Source

Featurebase support conversation #20 (customer iriahus), 31 Aug 2026 07:07 UTC; support reply 08:42 UTC "the expiration date shown is incorrect. We will fix it". Filed by Tim's assistant on 1 Sep 2026. https://trada.featurebase.app/dashboard/inbox/conversation/20