Issues with Secomapp seo booster- marketing

[bmdesign]

Been using there pro plan but due to some recent money issues I've had to cancel the service.. was so worried I decided to change to the free plan then delete the app. Since that day my site has been dead and some days no views at all. My store wasn't a hot spot before but definitely something wrong. I am no expert but I believe what they removed when removing the app has impacted my site.  Decided to Add the theme again and published it in the hope a new code would help but doesn't seem to of helped.

Does anyone have any suggestions on how its affected my store and ways to help? appreciate all feedback