MemberPress allows each new member a 24 hour grace period on recurring subscriptions. This gives enough time for the gateway to process the first payment and set up the subscription on its end.
Setup usually occurs almost immediately, but in some cases it can take up to 24 hours to complete (especially with Authorize.net). Without the grace period, the member would have to wait for setup to complete before they could access the protected content.
If you'd prefer that your members wait until setup is complete before accessing content, you can disable the grace period in MemberPress > Settings > Account.
If after 24 hours the subscription expiration date has not updated, there may be issues with your gateway setup or settings. Please be sure you followed the setup instructions for your gateway correctly. You can access the instructions to integrate Authorize.net, PayPal, or Stripe in the MemberPress integrations listings.