I registered for mtn shares since yesterday and it's still showing pending, so I want to know what is happening

Hi Yakubu, it may be a temporal system issue, but if your payment was successful, you will receive a mail from them. You can try it again later.
If the issue persist, You can contact their customer care via any of these channels.

Telephone – 080MTNOFFER (08068663337) or 070046837862452
Email – info@primaryofferng.com

Network issue