Welcome to Fishlore! I'm sorry to tell you, but the product Cycle contains the wrong sort of bacteria, and you will have to keep adding it forever to keep your cycle. The only product I know of that contains the right bacteria is Tetra Safestart.
Unless you can get your hands on some Safestart, you will have to cycle with fish, which means 50% water changes every day using Prime or Stress Coat + as your water conditioner. Both of these will detoxify the
ammonia for 24 hours, while leaving it available for the bacteria.
If your pleco is a common pleco, he will grow too large for your tank. Common plecos grow over a foot long and have a large bioload. They need 55 gallons minimum.
The test strips are inaccurate, most of the members here would recommend the API master kit. It uses liquid, and is very accurate. It can be a little pricey, but it is worth it in the long run.

I hope this helps. Good luck with your tank, and feel free to ask any more questions you might have. Cycling can be frustrating; I'm going through it myself for my 30g, but it's very rewarding once it's over.