Define your use first
A few short sessions each month and frequent long connections are different needs. Write down how often you connect, which device you use and which benefits actually matter to you. Choose against those needs rather than the longest feature list.
Questions about free access
Is there a usage allowance, when does it reset, where do ads appear and which locations are available? Free to download and unlimited free use are different claims. A one-week Premium promotion also does not automatically describe the features of the ongoing free plan.
Questions about a paid subscription
Read the monthly or yearly price, renewal terms and benefits offered to your account on the purchase screen. Do not confuse a yearly total with its monthly equivalent. Unless explicitly established, paying does not imply that every location is faster or that a particular website will become accessible.
Making a HarmanVPN decision
Try the connection on your device with the plan you already have. Compare the Premium benefits in the app and upgrade when they meet a need. Treat removing the app and managing a store subscription as separate actions: check subscription status in your Google Play account. Use the amount shown to you by the store as the applicable price.